K.C.
ETA: DO NOT get lactose free milk, as another poster suggested. Children with milk allergies are not allergic to lactose. They are allergic to the proteins in the milk, whey and casein.
My son drinks soy milk. It takes a little getting used to, but it's better than rice milk, which is really watery. You could make it chocolate milk, too. Silk has a chocolate variety you can buy, or Hershey's syrup is non-dairy.
A lot of people also say Almond Milk is good, but my son is allergic to nuts too, so we have to stick with soy. Soy also has more of the nutrients that you get from cow's milk - protein, fat, vitamins A and D. Most of the other milks lack at least one of these key ingredients.
Other good foods - lots of meat, vegetables, and fruit. Pretty much anything fresh like that should be safe.
Daiya brand soy cheese is a good one if you're looking for something that melts to make homemade pizzas.