My 3 1/2 daughter is exactly the same way and has been since she was about 2 1/2! She is getting better and I feel it's been a great night if she only gets up once! It feels like I've tried everything. I've figured out she can't have a night light because then it's too bright. But I did find a book "Moon in my Room", which is a night light book that turns off after 10 min? and she can push it to turn it on again. That seems to comfort her. Another thing, she feels comforted by, is leaving her bedroom door open! Also I really talk to her about what she's thinking and why she gets up, which she says "she needs to see her mommy!". Anyway after that one, I really re-enforce for her to stay in bed and that mommy is sleeping, and will see her at breakfast or when it's light out. But what I've mainly found is just being consistent with the routine, talking to her, and walking her back to bed whenever she gets up (so she doesn't get in bed with me!)
Good luck and it helps to know we're not the only ones!!!