Is there a word or phrase that neans someone who doesn't learn from his mistakes or makes the same mistakes again?
In the criminal justice world, they are known as repeat offenders. There is no reason that phrase could not be utilized (a bit poetically) to other spheres.
A similar term is recidivist
A common quote, often misattributed to Einstein, is
It likely was first used in publications by Narcotics Anonymous.
All people make mistakes. Most people make mistakes repeatedly. Some people make the same mistake very frequently before they learn. I would call them slow learners.