Our middle son has had sleep terrors also. Since my sister has suffered with them her whole life, we talked to her about what to do. She mentioned sugary stuff and liquids at night...sure enough when he has to pee, and ESPECIALLY when he has anything sugary (even fruit) after about 6:00, he has night terrors. Is your daughter a blondie? I think there tend to be blood sugar issues with fair kids more than darker-haired kids.
We now know that we have to be careful with him, but if we ever have it happen, it's very important to speak calmly and firmly, and tell him he's safe, I'm here, everything is okay...I can't let him cry it out because I know that even though he's not coming out of the sleep state, my little guy is terrified. I read that it's not good to wake them, just to hold them and calm them, and let them go back to sleep.
I hope that helps!
Good luck!