Sorry to say this but you are showing very "typical male" characteristics here! You didnt want her enough while you had her so you finished with her. She has done a bit of self improvement, got off her backside and got a life and suddenly you want her back. You want her so badly because you can't have her. She's now a challenge, bit of excitement. But at the end of the day she is who she has always been and if you do suceed in getting her back.... It probably won't last. Sorry to be harsh, but I think you need to look at your situation objectively instead of stamping your feet and crying it's not fair. Lifes not fair, most people on this forum know that only too well!
I hope you get what you want and if you do, you'll treat her better and accept her for who she is.:)