The road to hell is paved with good intentions. Hermione said it herself.
Perhaps Harry needs to step back and evaluate himself. He's doing a lot of preaching without learning from his mistakes. He also needs to keep reminding himself that while his former friends and enemies look the same, they are not the same people. He doesn't have to be the same either, he has unlimited opportunities to improve himself physically, mentally, emotionally, and perhaps most important, spiritually.
Author's response
Ah, but there's the rub, eh? It is easy to see the faults of others but difficult to see our own, even when they are the same.
Harry can change and grow in this world as he couldn't in the old, but will fate allow him?
BJH