In addition to asking for more, babies also need to be able to signal being finished. Teach your baby the sign for the word all done in baby sign language with the following description and video.
Hold the hands in front of the chest with the palms facing up and the pinkies touching. Pull the hands while rotating the hands to make the palms face down.
Beyer, Monica. 2006. Baby talk: A guide to using basic sign language to communicate with your baby. New York: Jeremy P. Tarcher/Penguin.