Make bedtime in her bed special. Tell her you are going to take her to the store to buy a special stuffed animal/book/blanket or whatever trips her trigger and tell her that it is her "special sleep in my own bed alone-toy". Then buy and egg timer and let her set it 10 min before it is time to go to bed and have a race into bed when the bell dings. Read a story, kiss her goodnight, turn out the lights, leave the room. If she gets up gently put her back in bed without a word, kiss her and leave the room. After a few times she will get the idea that you are serious. (I read somewhere that letting a kid get to sleep on their own teaches them independance)
Another thing I tried when I was a nanny was to make up a chart the kiddos name got some star sticker and for every night she went to bed and stayed there she got to put a star by her name. When she got an agreed upon number by her name we did something special like make cookies, went to a movie, got her a cheap toy (sometimes she chose).
