How do I make myself more attractive to her?

Hi, my girlfriend of two years broke up with me 3 months ago as I just wasn't confident in myself at all, she's now with another guy, but has said she has strong feelings for me and hopes we can work things out some day, just I want to be able to show her my more confident side and be generally more attractive to her in terms of not just relying on being cute, just any ideas would be most appreciated. Thanks