What would you do if your friend was like this?

So I have been friends with this girl for a few years now. We use to work together and we were very good friends but this past December I got a new job. We use to hang out about 2-4 times a week. Since December I think I have seen her about 5 times. I text her and she texts me A lot and when we plan a day to hang out but her plans always change or she waits till last minute to confirm a day to hang out and by then I always made other plans. So I wrote her a longggg email stating that I am done trying to be friends if she wont put in the time either. So I gave up and then she said sorry blah blah blah and we hung out one more time. But since then that was a a few months ago nothing. texts but once every few weeks shes like OMG I MISS YOU we need to hang out! But never sets anything in stone or if I see her out around town she runs to me hugs me and tells me we need to hang out. Should I give up on the friendship? Should I try something different to get it through her head? I am 22 and she is 19. It might be we are just in different stages in life shes going to school and has a boyfriend and all this stuff and I just bought a house with my fiance and have a career so maybe we just don't work as friends anymore? IDK What do you think and input with be helpful! Thanks!