She's on the fence what do i do??

So summary:
-Dated a girl for 4 years
-Broke up cause she lost feelings for me
-I worked on myself hard for 5 months
-She sees me for the first time and is instantly attracted to the new me.
-We hang out lots and sleep together within days.
-I ask her out again and she says she doesn't know.
-I tell her I don't care what her decision and I don't feel like sleeping around with no commitment anymore.
- I tell her fine lets not get back together and she gets sad, but when i say let's get back together she says "I don't know."
- We talked about our problems and how we could fix them all in a relationship

I'm getting REALLY frustrated

She tells me she loves me and misses me constantly.

It sounds like she is playing games. She doesn't want to be with you but she doesnt want to be alone, either. Hence the i dont know. She knows alright.

Reading between the lines, it seems that she dumped you because you let yourself go a bit, and now that you are all buff again, she wants to jump your bones. Despite telling you she loves you and all that, it seems that all she's really interested in from a man is a sexy appearance that turns her on physically.

Most women aren't that superficial, so why not take advantage of the "new you" with someone who is looking for more in a relationship than just getting laid?

Carl.