If a crown won't stay in? options?

I've always had trouble with my teeth. Finally was able to get crowns and braces last year. My teeth are finally starting to shape up nice and now im losing a crown (whole tooth.. middle left side). I had to get it crowned because it had cracked down the center. The dentist said that the root was fractured and the crown didn't have much to adhere to and i could lose it. It was fine for awhile. Anyone have input on options? Thank you.