Hello, is there any possibility you could get her to settle on just regular Purina Dog Chow? Here it actually cost less than Purina Beneful but I think it is a better food. Definitely DO NOT go with Pedigree in my personal opinion as it is preserved with BHA/BHT. Purina Beneful has actually about the same ingredients as Purina Dog Chow except in its label you find sugar which in my opinion makes it worse than the regular Purina Dog Chow. Here is a link that compares the ingredients in the food.
http://www.feedmypet.com/dog-food-comparison.html