I'm sure she just wants to be close to you at night. How big is her bed? Can you snuggle with her in her room to get her used to falling asleep there? Around age 2-3, children's imagination really starts to develop, and she may be experiencing bad dreams for the first time.
I used rewards with my daughter at that age and put our dog in her room at night, and it worked - for the most part :). I picked up a slew of inexpensive things I knew she would like and put them all together on a tray. I told her that if she slept in her own room for the whole night, she could pick anything she wanted off the tray the next morning. After 7 days of sleeping in her own room, I increased the time to 2 nights before she picked something and so on, until the rewards were weekly and involved us doing something together in lieu of a physical prize. Six months later, she regressed to coming to our room again. Our solution was to allow her to sleep in the same room as her twin brothers (1 year younger than her). She hasn't come out since and the three of them love sharing the same room - go figure.
Moral of the story: she probably just wants someone to sleep with and she may go in and out of managing that need until she's older and wants privacy. Having a pet to sleep with or rewarding the accomplishment on a regular basis may help her through it. The rewards were so much easier than trying to force her and hearing her cry. With my eldest, our bedrooms were across the hall from each other, so I arranged his bed so he could see us and that curbed his need to visit us each night!
Wishing you many restful nights!
A