As we all knew already, Emilie will be back as Belle on Once Upon a Time. Her episode will air in May (I think she will be in the season finale). Here's a little article that confirms her return officially.
De Ravin, who plays Rumpel’s true love Belle, will reprise her role in an episode airing next month. While her fairy tale character was recently seen giving love advice to dwarf Grumpy, it’s been a while since viewers have glimpsed her Storybrooke counterpart, who has been locked up in a ward by Regina.