If she is cold, clammy, hard to waken, or breathing irregularly then please take her to the hospital because these are signs of alcohol poisoning.
Otherwise, just let her sleep it off. Be sure you stick around and look after her to make sure she does not vomit in her sleep and possibly choke. Also, wake her up periodically to make sure she's still okay.
She could also be dehydrated from the alcohol which could be making her feel worse. Keep having her try to drink liquid; anything at this point is better than nothing (well, except for more alcohol). Maybe a little food or hard candy to suck on will help her queasiness especially if it's been a long time since she's last eaten (low blood sugar can make you feel ill as well).
Other than that, hope she learns her lesson. For many of us, once is all it took
