Because of all the tasty flavors already in the recipe, I promise you that using 1/2 cup water instead of 1/2 cup wine wasn't an issue. But, just in case you were wondering, here are some alternatives.
Chicken or Beef Stock. This seems to be most common.
Better Than Bouillon. This one is my favorite. It adds wonderful flavor as well as color. It's pretty salty, though, so use sparingly.
Apple, Grape, Cranberry or Pomegranate Juice. It makes sense. Wine is made from fruit juices.
Apple Cider Vinegar. I'm already using Balsamic Vinegar here so I wouldn't want to overdo it.