She's waking up and bored, so it's time to find you for entertainment. You get out of bed and walk her back to her room, probably tuck her in with a kiss and hug and she feels great. All this warm and fuzzy attention!
Let her know before bed time that you can't get out of bed to put her back in because Mommies need sleep too! Make sure she has some favorite books or plush toys or dolls she can talk to - but nothing too entertaining that will keep her up herself.
When she comes into your room tell her it's sleep time and she needs to go back into her room and she can look at her books or talk to her doll if she is not tired right away. Then don't get out of bed - she made it to your room, she can make it back to hers. She is old enough to get into bed and make herself comfortable with her blankets etc. Just make sure you stay awake long enough to hear if anything goes wrong...
She's used to the attention in the middle of the night, so she may not like this and may cry at your bed or start to say she is scared if it gets you to do what she wants. Be prepared to either let her cry it out at your bed or continue to walk her back to her room.
My kids didn't get up too much in the middle of the night because I never got out of bed for them - just sent them back, but my daughter (who is 6) likes to come out of her room before she falls asleep. To combat this, we bought 3 fake flowers of her choosing and she can use them in exchange for coming out of her room - for whatever she wants -- potty, get another book, hug and kiss, just see what we're doing etc. If all the flowers have been exchanged and she comes out of her room, we start taking her favorite things out of her room in exchange. This has worked wonderful in our house. For the middle of the night, you may want to use just one flower if you feel her reasons for coming out are legitimite.