When I was ready to break my DD's middle of night feedings, I started introducing very diluted juice. She was already on solids, and consistently slept all night with only rare occassions of night wakings. Up until that point, she was about 7 1/2 months old, I resigned myself to giving her her bottles of formula when she did wake up at night. Obviously younger newborns / infants actually need that middle of the night nourishment so it shouldn't be denied.
For about a month I gave her diluted juice which seemed to discourage her from waking for a bottle. Around 9 months I was introducing her to the sippy cup in preparation of transitioning off bottle, so I started only giving her juice in sippy when she woke at night. Then I moved to only water around 10months, also only in a sippy. She wasn't too delighted in the changes, but she quickly adapted. I was lucky.
My baby girl is 6mos. old. She has a 6oz. bottle every 4hrs. or so (with a fruit in the morning and a veggie in the evening). We give her 3oz. of diluted apple/prune juice every day (in sippy cup) for constipation. I know when she wakes up, it is only out of habit. Plus, our Ped. told us to cut them b/c she doesn't need the extra calories (she's a chunky monkey!). But she usually wakes 1-3 times a night wanting a bottle. My sister told me to try giving her water, but she will only take 2oz of water and then want formula. I didn't think to give her juice. It doesn't keep her up or make her hyper at night?
You could try gradually diluting the formula until it is all water. My son was still not able to go all night without a bottle at 6 months. What time is her last feeding? Maybe you could try pushing that back and then giving increasingly watered down formula.
We have been trying to give her a bottle after her bath (around 8pm), but sometimes she just isn't hungry then. I will tell my hubby about the diluted juice and/or formula and see how that works. I am glad it's a long weekend..lots of time to work on it!! Thanks!!
Update: We started giving her between 4-6oz a half hour before bed. The first 3 nights she still woke up and whined and tossed and turned for about 2 hours, then went back to sleep. For the past 2 or 3 nights she hasn't woken up at all, and is sleeping in her own room. YAY!!!