if she's not in it, she's not in it. Theres not really much you can do to change that. The more you focus on trying to win her back, the more it'll hurt when you fail. :edit: If things are different since she's back or it feels wierd or something now, it probably means the "spark" as you call it is already gone... you may be more in love with the ideal than the person herself.

Take it from a guy that took the better part of a year recovering from his first dumping: do your best to move on.