When you go through Confirmation, do you receive something physical that proves it? And if so, do you have to go through Confirmation again if you lose it?

Everyone who receives the Sacrament is sealed with the Gift of the Holy Spirit and there is a mark on our souls that never goes away. Some parishes will distribute certificates. If you lose the certificate, you do not need to receive the Sacrament again! You cannot be re-confirmed. Once you are confirmed, it is for life. The record of your confirmation is held at the parish where you were confirmed and is also noted at the place of baptism. So, there is no need to go through the Sacrament of Confirmation if you lose the certificate you received. You don’t become unconfirmed if you lose it!