If she's not eating either, then whatever you give her needs to be as nutrient dense as you make it. I know that we automatically think "water" when we think about hydration, but the Brewer Diet got me thinking differently. Dr. Brewer did not recommend drinking water for pregnant women. He felt that when you can only hold down a certain amount of food and liquid them water was a waste of stomach space because it has so few nutrients in it. So he recommended that they drink nutrient dense stuff instead of water.
Some ideas are soups, stocks, broths, juices -- or better yet, whole fruits (if you can get her to eat them). The electrolyte drinks might help too, although not as nutritious. But remember that too much of certain juices (like apple juice, and even the electrolyte drinks) can cause diarrhea. So give her a variety. And the baths are a great idea.