I hope she'll be OK!
Providing some extra heat will be helpful. You can do this by putting a heating pad under half the cage, or by covering one end of the cage with a towel and shining a lamp on it so the heat goes through the towel and into the cage. Be careful that the lamp isn't close enough to set the towel on fire! The reason for heating only one side of the cage is so she can move if she gets too hot.
It's also very useful to provide electrolytes. I don't know whether Ribena serves that purpose or not, it probably provides sugar but maybe not the salt. The usual way to provide electrolytes is with Pedialyte or a sports drink like Gatorade. There are also simple recipes for making your own: http://www.webmd.com/hw-popup/rehydr...navbar=hw86827