Hi N.,
I just went through the SAME situation with my 13-month old son a few weeks ago. For the last 2 months, he started waking up crying 1-2 times per night; sometimes wanting a bottle.
A friend told me his doctor gave him great advice when his kids went through it (apparently it's common).
You need to "reset" their bedtime clocks...For 4 days you need to change her bed time. Example, if she currently goes to bed at 7:30 p.m., have her go to bed at 7:00 or 8:00 for 4 nights. No more, no less.
Do not get up when she cries (unless you think something is wrong with her).
I know it sounds too simple to work, but we were SHOCKED when our son went right back to sleeping through the night after only 4 nights of changing his bedtime by 30 mins. He hasn't woke up in the middle of the night since.
Good luck!