Baptism and Confirmation “leave an indelible mark on the soul” - they change the soul in an irreversible way and so are not repeatable. Once the change happens, you can’t change back. The big word is ontological change - the very nature of the being is changed.
The other sacrament that imparts an ontological change is Holy Orders. It is “repeated” as there are 3 degrees of orders - deacon, priest, bishop. I put quotes around “repeated” because the sacrament is the same, but the prayers and intention are different each time a person is advanced through the degrees. It is not repeated in the sense that a person can not be ordained a deacon, priest, or bishop multiple times.
Reception of the Eucharist does not have the same effect, and so can and is repeated.