No, the change in plaster of Paris cannot be reversed.
When water is added to POP, it undergoes a chemical change. Its composition changes and is converted into another substance. Since it is a chemical change, so it cannot be reversed. Making statues out of plaster of Paris is an irreversible change because plaster of Paris has a property of setting into a hard mass on getting mixed with water due to the formation of a new compound. The hard mass cannot be converted back into the previous plaster of Paris . Hence, it is an irreversible change.