As soon as priority number 1 becomes pleasing yourself. I'd be willing to bet you'll find yourself doing some incredible things for her, not because it makes her want you, but because it makes you feel good. There is nothing selfish about doing what makes you happy, because you'll find that if you are REALLY in to her, the selfless acts will make you the happiest. No woman wants a lapdog (not trying to imply that you are...but beware), at least not for long.
I would ask yourself why she broke up with you. Then I would ask yourself why should I give her a second chance. Like HF said, she may do it again...why? What did she need that she couldn't find in you? What do you need from her. Be careful of wants and needs.
Love starts with yourself...