Since the entire earth burns and is dissolved at the coming of Christ again, how can there be any unsaved ungodly survivors left to repopulate a burned out and dissolved earth? An earth that in premill thinking is the same one as today.
Scripturally there is only the old first earth, then the New regenerated earth.
Our resurrection and the regeneration of the world as the new earth, in which there is no more evil.
The unbelieving are killed by Christ in fiery destruction and judged.
2 Peter 3
This second epistle, beloved, I now write unto you, in both of which I stir up your purity of mind by way of remembrance,
2 that ye may be mindful of the words which were spoken beforehand by the holy prophets and of the commandment of us, the apostles of the Lord and Savior,
3 knowing this first: that there shall come in the last days scoffers, walking after their own lusts
4 and saying, “Where is the promise of His coming? For since the fathers fell asleep, all things continue as they were from the beginning of the creation.”
5 For of this they are willfully ignorant: that by the Word of God the heavens were of old, and the earth standing out of the water and in the water,
6 whereby the world as it then was, being overflowed with water, perished.
7 But the heavens and the earth which now are, by the same Word are kept in store, reserved unto fire against the Day of Judgment and perdition of ungodly men. (judgment of hell awaits the wicked at Christ's return)
8 But, beloved, be not ignorant of this one thing: that with the Lord one day is as a thousand years, and a thousand years as one day.
(time to God is not like men look at time, the 2000 year delay of Christ's return for example is God building His church)
9 The Lord is not slack concerning His promise, as some men count slackness, but is longsuffering toward us, not willing that any should perish, but that all should come to repentance.
10 But the Day of the Lord will come as a thief in the night, in which the heavens shall pass away with a great noise, and the elements shall melt with fervent heat. The earth also and the works that are therein shall be burned up.
(Christ always describes His second coming as like a thief coming in the night, at an unexpected time)
11 Seeing then that all these things shall be dissolved, what manner of persons ought ye to be in all holy manner of living and godliness,
(Since at the return of Christ, all things will be changed, and our former lives no more we should look towards the eternal state, not this current world as it will be gone-destroyed)
12 looking for and hastening unto the coming of the Day of God, wherein the heavens, being on fire, shall be dissolved and the elements shall melt with fervent heat?
13 Nevertheless we, according to His promise, look for new heavens and a new earth, wherein dwelleth righteousness.
14 Therefore, beloved, seeing that ye look for such things, be diligent that ye may be found by Him in peace, without spot and blameless.
15 And account that the longsuffering of our Lord is salvation, even as our beloved brother Paul also, according to the wisdom given unto him, hath written unto you,
16 as also in all his epistles, speaking in them of these things. Therein are some things hard to understand, which those who are unlearned and unstable wrest, as they do also the other Scriptures, unto their own destruction.
17 Ye therefore, beloved, seeing that ye know these things beforehand, beware lest ye also, being led away with the error of the wicked, fall from your own steadfastness.
(Unstable people, ignorant of the plans of God will change, wrest, and distort the scripture in the time of the end as perilous times will come and many be deceived, evil men and seducers shall wax worse and worse, deceiving and being deceived. )
18 But grow in grace and in the knowledge of our Lord and Savior Jesus Christ. To Him be glory both now and for ever. Amen.