Very briefly, I put them together with the passages indicating rebels are restored after not surviving (Isaiah 4, where the penitent rebels who seek and receive reconciliation and purgation by the spirit of judgment and the spirit of burning, are strongly contrasted to the righteous remnant who are described as the “survivors” of God’s prior butt-kicking wrath);
after being punished until they are neither slave nor free (a poetic way of saying they are punished to death, Deut 32:36 and surrounding contexts, after which He shall have compassion on His rebel servants and vindicate them, for they shall repent of their idolatries and return to loyally worshiping God Who puts to death and gives life, Who has wounded and now heals: thus explaining what His vengeance against His Jewish and pagan adversaries involves, and also why the nations shall rejoice along with Israel);
and after being punished until His rebel children no longer exist (Jer 31:15ff, where righteous Israel, typified as Rachel, weeps inconsolably for her children, rebel Ephraim, because they are no more–which Matthew’s connection to the slaughter of the innocents clarifies means they have been slain–but God can console her because He promises to bring rebel Ephraim back from the land of the enemy when He hears Ephraim grieving and penitent in his chastisement: God surely has not forgotten him and will surely have mercy on him! Which shall be accomplished somehow by a mysterious riddle where God does a new thing involving a woman encompassing a man.)
In short, there is more to the story afterward when read this way, and so (to me) the story makes more sense; but if annihilation is the end of the story, then it becomes harder (for me, or for anyone really) to figure out what the scriptures which seem to be indicating more of the story can be referring to when talking about those who have been slain out of existence.
Also, God Himself specifically says He has less than no interest in annihilating anyone. Isaiah 58:16-19: God promises that He shall not be angry forever (or to the horizon) at rebel Israel whom He smote, precisely because if He was angry forever at them then the souls He made would be annihilated! Instead, God will not hide Himself forever from rebel Israel, but rather will heal him, lead him to restoration of comforts, and even lead him to his mourners (comforting the righteous remnant, too)! God intends peace to him who is far off (rebel Israel by context here) as well as to him who is near (righteous Israel by context) and so will heal the one who is far off. Not be angry against him forever (in ECT), and not annihilating him.
Even the bronze serpent from Genesis 3:15 (i.e. Satan, i.e. Leviathan), despite being prophecied to be slain at last by YHWH (Isaiah 27:1) shall end up eating his dust in peace living on God’s holy mountain (Isaiah 65:25). But that’s because, even in regard to Leviathan, God has no wrath in Himself but only goes out to war against those who come to war against Him with thorns and thistles–which He burns up, so that they cannot fight anymore, and will cling to Him instead making Him their friend. (Isaiah 27:4-5, in the midst of a bunch of prophecies of God kicking the butts of the unrighteous, up to and including Leviathan back in verse 1.)
Anyway, there are a bunch of things like this in the OT, even though sometimes a prophet (as at Psalm 37) only talks about the destruction of the wicked and not their repentance after being destroyed. But logically, if one prophet (for example David) expects God to destroy evildoers utterly, and if another prophet (for example Asaph) pleas with God to destroy evildoers to the limit so that “they may seek Your name O YHWH”; then the goal for the total destruction has also been revealed, and the goal is not permanent total destruction for the evildoers (neither in ECT nor in annihilation).
The Asaph prophecy I’m talking about is Psalm 83, where at verses 13-18 in the middle of a large number of standard pleas for YHWH to punish evildoers to death, including a plea that they may be confounded and troubled “olam” (to the limit, often translated “forever”), the rationale is given “that they may seek Thy name O YHWH” and “they may know that You Whose name alone is YHWH are the Most High over all the earth.” The latter might not necessarily involve repentance and salvation, but the first certainly does!
Even David, as fierce as he can be regarding the coming destruction of the wicked, receives enough revelation on the topic to do things like use a verb indicating benevolent purpose when describing the Messiah ruling in the midst of of the kings of the earth He shall shattering and the (single) head over men He shall shatter, per Psalm 110. Which has direct connection to Rev 19, which in turn also has direct reference to Psalm 23 of all things! (But Psalm 23 is rather more kick-ass in the Hebrew than our English translations tend to render it. Wouldn’t want to scare or disconcert the pious with images of mercy and goodness most certainly running us down like a king pursuing a rebel army to overthrow and destroy them!–the rod of YHWH is supposed be a good thing, for which we hopefully pray in regard to ourselves, not a good thing for those rebels over there whom God is running into the ground.)
St. Paul, in 1 Cor 15, when talking about the rulership of Psalm 110, apparently understands that David intended the verb to be benevolent toward those ruled, because he explains it by reference to the benevolent rulership of David’s Psalm 8:4-9, where the strength against the satans and those who seek revenge comes from the mouth of infants and nursing babes, the most harmless and innocent: and it is specifically this strength by which YHWH, in the Day of YHWH to come, shall make satans and those who seek revenge “to cease” elsewhere in the Psalm. Those who seek revenge shall not be ruled by those who are seeking revenge in turn against them, but rather by a different and wildly unexpected strength. The “cessation” of the satans and those who seek revenge must be consonant with that benevolent rulership.
David even seem surprised to hear, at the end of Psalm 62, having finished his warning against oppression and his hope of God’s refuge from treachery, that “One thing God has spoken; These two things I heard; That power belongs to God; and lovingkindness is Yours, O Lord!–for You {shawlam} a man according to his work!” Power and lovingkindness are the same thing in God (according to the revelation), so power expressed in punishment of sin must still be also lovingkindness toward the person being punished (and most places in scripture which reference the coming payback from God tend to mention this in connection to coming punishment). Notably, the verb {shawlam} supports this: it’s a primitive word meaning ‘to make safe’, related to the word for peace, and involving by metaphorical application several actions with beneficial intentions and goals for the one being acted toward, such as fairly paying, completing, saving, being friendly, making amends, to perfect, to make good, to make prosper, to make a peace treaty. That’s what the coming payback, even to the wicked, is about!
Okay, that wasn’t put so briefly. Sorry. Like I said there’s a lot of this sort of thing in the OT. But you asked how I deal with one common type of verse in the OT, so I thought I should answer.