Hi T.,
I also feel your pain. My son did this from the time he went into a bed, until he was around 8. At first, he would come in when I was still awake, and I would take him back to bed every time(had to do the whole monster ritual sometimes up to 3 times a night), but then, just when I thought I had it licked, he started waiting until I was asleep and coming in, and I'd find him in bed with us who knows how many hours down the road later. Most of the time I'd still take him back to bed, and sometimes my hubs would take him if it was a PT morning, but on weekends he'd manage to stay there most of the whole night alot of times. Like I said, he finally grew out of it--at 8.
My youngest is 9, and when she was small and was afraid, my hubs would let her come sleep with us, and it got to be a real problem, to the point where we might as well have been considered co-sleeping because she rarely(like once a month *maybe*) slept in her bed. This went on from age 3 until around age 7.
To this day at 9 years old, she still has nights where she wants to sleep with us, and if there's the rare storm, I can guaranTEE you she'll be in bed with us. She is a kicker, thrasher, and cover thrower offer, and makes sleeping miserable, and her dad hates it, but he's the one that started us down this road.
My only advice is like everyone else said, be consistent. I like what Amy did whe she had special nights her kids could sleep with her. My daughter had 2 Fridays up until school let out, and when it starts up again, I don't think we will continue it. She hasn't asked very often during summer break, so I think I'll just continue to gently refuse to let her until she stops asking. But having a special night she could depend on kept her from asking or trying other nights. Maybe with your daughter, you and her could pick out a calendar and mark the days when she will sleep with you, and give her a sticker on her calendar for every night she doesn't try and sleep with you when it's not her night. Then, she gets some sort of reward, until the special night becomes ingrained as the special occasion she can look forward to. When she's older, you can gradually work up to stopping it altogether.
Best of luck. I know how tiring it is.
K. W