do you think she could be teething?
my 8 month old starting sleeping right through at 9 weeks, then at 5 months started waking up to 5 times a night. She wasn't fully waking up but just having a bit of a moan in her sleep, and when we put the plug back in gave her a dummy, she immediately went back to sleep.
She was sleeping in her own room at this point, but we moved her back to ours, as by the time we got to her, she was waking herself up. Since she came back into our room, it's just a case of leaning over, popping her dummy back in and she's straight back to sleep.
In the last couple of weeks she's had 2 teeth come through, and she now seems to be settling down at bit (slept right through the last 2 nights - bliss!) so fingers crossed for more.
We have been giving her a 'shot' of nurofen before her night-time bottle (which we changed to Hipp's Goodnight milk, seems to keep her full all night, she hasn't needed a night bottle since we switched), maybe you could give that a go?
My only problem now, I wake up in a panic that she's stopped breathing as she's sleeping so soundly! 
Hope all that helps a little! Good luck.