Hi Jen-
I went through the exact same problem with my son (now 12 months) when he was about 9 months old. I consulted the book my pediatrician gave us "American Academy of Pediatrics Caring For Your Baby and Young Child". There's a ton of great info in this book and it always reminds me that whatever challenge we happen to go through is normal and gives advice on what to do.
A very abbreviated version (see pages 258-259 if you pick up the book)for what they suggest is this:
As separation anxiety intensifies she will start to resist going to bed and wake up more often during the night (4-6 times a night) looking for you.
She just needs to know that you are still there when she wakes up. And she needs you to teach her how to fall back to sleep on her own.
They suggest to not do anything to "reward" her for calling for you during the night. They suggest going to her side to show her that you are still there (and make sure that there isn't something really wrong with her).
I go in, give my little guy a hug tell him I love him but that it's time to sleep. I lay him back down and walk out. I go back in every 5- 10 minutes. Beware that she will be MAD when you walk out but eventually she'll learn to put herself to sleep with little to no crying. It's an EXHAUSTING process but it worked for us. Also beware that she may revert back to doing this each time a tooth comes in (we've just gone through it the past 2 weeks with tooth #9). If you figure out that it is a tooth ( I think another poster mentioned this) Tylenol may help her to go to sleep more smoothly and not wake up quite as often.
Sorry for the super long post. I hope this helps!