Only apologize once (and mean it) and demonstrate your dedication to fixing things with maturity and accountability. Cant rebuild old trust, need to build up a new trust. Make plans in your professional life, hobbies, health and relationship and stick to them to demonstrate you're a man of your word.
In other words take responsibility and be a man. At the end of the day it's her choice to stay or not and you can't control that unless you're Ike Turner. Moreover, those plans can serve as a cushion if she does leave and can keep you out a hole of depression or rejection.