Life is so ironical, sometimes, the person you love the most will not show interest in what you are trying to offer her. But sometimes a relationship is just a choice. For instance, have you ever seen a couple and wondered how they came to be? Well, they made a choice to be. You as well can make the person you like to like you back.
Recreate your image
Probably you were not looking as appealing to her as she would like. For example, there are women who never like seeing you in official wears, others just hate your casual look for no reason. Get back to the drawing board and correct the "mistakes" that you had earlier made. You need to look more appealing, perhaps the long hair you are keeping looks dirty, cut it to size and step out looking brand new.
Do not be pushy, listen to her
At first, she said that she doesn't like you or perhaps she behaved in such a manner, you have come back re-branded and you still want her. If I was you I will never come back, but anyways, you have your reasons for coming back. Do not start the story where you left it, this time pretends that you are not interested, just get her to like you your company first. In case she is not interested in getting out, do not force it, just accept and be patient, you will win.
Show that she matters
It is up to you, to prove to her that she is losing the "best" guy who would ever grace her life. Be gentle, caring. Do not overdo this, she might think that you are desperate. Stop this "I love you, I need you" narrative, believe she hears that from at least five people every day. To win her, you must put this narrative into action.