Here's my list of locations that carry Tofutti (soy) and Rice Dream ice creams. It was valid at the end of February but I'd confirm with Brenda that nothing has changed.
Magic Kingdom: Plaza Ice Cream Parlor, The Cone Shop
Epcot: Fountain View, Liberty Inn, Sunshine Seasons (Land Pavillion)
Animal Kingdom: Restaurantosaurus
Hollywood Studios: Hollywood Scoops
A few extra cold snack options at the outdoor food carts all over the parks include:
frozen bananas, itzkadoodle popsicles, strawberry bars
Even the popcorn at the carts is dairy free.