You just described the real change that we are being called to.
You're only missing the name for it.
"We can't go back and start over..." That's exactly why Jesus said you must be born again (John 3:3). Not reformed, not improved.
Born.
A second start you cannot give yourself, because nobody births himself.
"Put on a new personality" is nearly word-for-word Ephesians 4:22-24: put off the old self, put on the new. And the slavery language is Paul's too: "slaves of sin" set free (Romans 6:17-18).
The innocence you're reaching for isn't recovered by going back. It's received: "though your sins are like scarlet, they shall be white as snow" (Isaiah 1:18).
Twenty years of chains and you walked out. There's a Person behind that door, and He can return you to innocence.