HI. Mine used to do that too. I think they go in phases, but i totally agree that you need to address now. Otherwise, no rest for you. By falling out, do you mean that you switched her to a toddler bed? Maybe she is too young for that. Mine is almost 16 months, and I don't want to switch her yet for the same reason that she will just not stay still and start playing instead of sleeping.
I agree with the previous post about a routine. Our routine is bath (every other day), brush teeth, change to PJs, watch 10 minutes of Sesame Street with the lights dim, then we say good night to Daddy, walk to bed, put her in the crib, and I read for about 10 minutes, kiss her good night, turn off lights and walk out. In her crib I she has 3 stuffed animals, that if she is not fully tired when I put her down she still can play around with her toys before she fully falls asleep. She does cry sometimes and wants to come out, but I just ignore her, or if it gets bad, I send her Dad in becuase if I go in to check on her, I make things WORSE!!
Hope this helps.