What do you mean by Regeneration..?
In Matthew 19:28 Jesus is talking about the Kingdom which we pray for.
Look at other translations
(BBE) And Jesus said to them, Truly I say to you that in the time when all things are made new, and the Son of man is seated in his glory, you who have come after me will be seated on twelve seats, judging the twelve tribes of Israel.
(CEV) Jesus answered: Yes, all of you have become my followers. And so in the future world, when the Son of Man sits on his glorious throne, I promise that you will sit on twelve thrones to judge the twelve tribes of Israel.
(ESV) Jesus said to them, "Truly, I say to you, in the new world, when the Son of Man will sit on his glorious throne, you who have followed me will also sit on twelve thrones, judging the twelve tribes of Israel.
(GNB) Jesus said to them, "You can be sure that when the Son of Man sits on his glorious throne in the New Age, then you twelve followers of mine will also sit on thrones, to rule the twelve tribes of Israel.
Tit 3:5 Not by works of righteousness which we have done, but according to his mercy he saved us, by the washing of regeneration, and renewing of the Holy Ghost;
When Paul talks about it in Titus--he is talking about our New Creature. The New life we get in Christ. We get that life ahead of the world of mankind.