Hello, Mrs.Pinette
The food in the Summer Palace is, by any means, expensive. You can not reenter the place after lunch. There are many snack bars in Summer Palace. You can buy snacks there, however, i suggest you have meals outside Summer Palace and then take some food with you in case you are hungery.

Hello Mrs.Pinette
The food inside the scenic spots is a little expensive. If you go out for lunch, you should purchase the tickets once again. Please prepare some snack in advance.