Understanding how to make her fall in love again begins with recognizing that right now you two need to be apart. Something in the relationship wasn't working. Break ups don't randomly happen unless there was a problem. If your ex girlfriend dumped you, and she told you why, you have to focus on that. If she didn't give you an explanation, it's up to you to determine what happened and what you can do to change it. Whatever wasn't working for her is what you need to concentrate on. Work on improving who you are as a man and a partner. Become the man you know she fell in love with. Unless you change what wasn't working, a reunion between the two of you will only end in a break up yet again.
Another key part of the puzzle of how to make her fall in love again is to create a new connection with her. In order to move forward from the tainted feelings of the break up, you both need to start fresh. Developing a platonic friendship is one of the best routes to take.
Friendship with your ex may not be what you had in mind but you have to view getting back together with her as a process. If you two can develop a mutually respectful friendship in which you're supportive of one another that will lay the foundation for a stronger romantic relationship in the future.
Approach her with the idea of being friends. Let her know that since you're both still recovering from the break up it may be good to stay connected on some level. Stress to her that a platonic friendship is really all you're looking for at this point. Then prove that to her by being helpful and trustworthy. Don't crowd her or contact her all the time. Just treat her as you would any friend. Be kind and considerate and slowly work at getting her to open her heart up to you again. It may take time, but you love her and you know she's well worth it.