...This game is so long it's not realy worth starting over...
Yeah, it's called New Game...
I see a conflict here.
To answer you question though, yes I have. There is no way to reverse any skill/stat point decisions (unless you're on PC). Since you don't want to start over, you will have to live with it and continue on.
Me, I stopped playing my mage because I didn't like how I progressed and picked skills. Haven't deleted him (yet), but I will probably start a new one once I finish the game with my melee or archer.