Will the people who followed Satan in the pre-mortal life be given a second chance? Such as, after they left, they immediately regretted it and they wanted to go back, Would they receive a second chance at life?
You assume that they didn’t already get a second chance (and have already rejected it as well)… Those who followed Satan in the Pre-Mortal life to the point where they came out in open rebellion against God and became Son’s of Perdition did not get there by accident. They made the choice to reject the atonement of Christ knowing full well what it would cost them.
God will forgive everyone that will truly repent and come unto Christ. Sons of Perdition are called such by God because they have shown that they will not repent.
Thus your question becomes a logical paradox. If a Son of Perdition were to repent then they would be forgiven… Which would mean that they really weren’t a Son of Perdition to begin with, which would mean that God was wrong to judge them to be a Son of Perdition. Which would be a mistake that God doesn’t make.