Q. When Catholics receive Confirmation but leave the Church for a long time, do they have to receive Confirmation again when they return?
A. The sacraments of the Eucharist, Reconciliation, Matrimony, and Anointing of the Sick can be received more than once. Confirmation, however, is one of the three sacraments that can be received validly only once.
Why is this the case? Because these three sacraments — Baptism, Confirmation and Holy Orders — leave an indelible mark on the soul. That is, each of these sacraments imparts to the soul a specific character that will always remain. (See the Catechism of the Catholic Church, par. 1304–1305).
For this reason, each person receives Confirmation only once, just as each person is baptized only once, and priests receive Holy Orders (are ordained) only once. There is no need to repeat Confirmation, even if a person has been away from the Church for a long time. That indelible mark remains on the soul. Such a person need only return and be reconciled to God and the Church through the sacrament of Reconciliation, so that the graces of Confirmation previously received can have their full effect.