As I understand it, many Catholics mark the sacraments according to the human lifespan. During infancy, children born in Catholic families would be baptized. Around 7 years of age, children would typically have their First Holy Communion. Around 14 years of age, children would typically have to take confirmation classes and be confirmed. Okay. So, let's say a Catholic doesn't really pay attention to Sunday school or confirmation class or thinks the theology is too confusing and dense or falls half-asleep in class due to boredom. And the only reason why he wants to get confirmed is that his family has a tradition of giving out confirmation presents. In adulthood, the Catholic tries to be a good Catholic, but the information that he was supposed to learn never got encoded into his memory. Plus, he might pick up some heretical information from a Lutheran friend or a Quaker friend. If the priest suspects that such a person is completely ignorant of Catholic theology, would the priest recommend a re-catechism and re-confirmation? If the said person confesses that he has completely forgotten everything he learned, then can such a person receive a re-catechism or re-confirmation, or is it too late as he was already confirmed? Basically, I am just wondering whether Confirmation is an one-time deal in life or can be given out despite that the individual is already confirmed (however poorly catechized he might be).
The Catholic canon law 889 §1 says that those eligible to be confirmed are: "Every baptized person not yet confirmed and only such a person is capable of receiving confirmation" (My emphasis).
Confirmation cannot be administered more than once. In the Catechism we read:
1304 Like Baptism which it completes, Confirmation is given only once, for it too imprints on the soul an indelible spiritual mark, the “character,” which is the sign that Jesus Christ has marked a Christian with the seal of his Spirit by clothing him with power from on high so that he may be his witness. [Cf. Council of Trent (1547) DS 1609; Lk 24:48-49]
As for continuing catechesis, this is not only necessary as we grow, anyone who takes their faith seriously will continue to learn and grow.
Someone who wants to be a good Catholic but is ignorant of much of the faith should definitely learn the faith, either by studying on his own or by being taught. A parish priest would be obligated to help such a person learn, either by teaching him himself, or by arranging for him to be taught by suitable catechists, or by facilitating self-study if he sees that the person is capable of learning that way.
As for re-cofirmation, the other answers have correctly pointed out that the sacrament of confirmation cannot be repeated. There is, however, a possibility, in the situation you described, that such a person's first "confirmation" wasn't valid, in which case he could be (not re-confirmed but) confirmed. Quoting from Fr. Heribert Jone's book "Moral Theology" (which is, to the best of my knowledge, a respected, traditional, Catholic treatise): "Valid reception of Confirmation requires that the subject be baptized. Of those who have attained the use of reason, it is furthermore required that they have at some time made at least the implicit intention to be confirmed and that they have not revoked this intention." I'm not sure whether intending to go through the ceremony in order to get presents constitutes an intention to be confirmed. So a person in the situation you describe should consult his pastor for advice on whether the previous confirmation was valid. If it's not clear whether it was valid, then the sacrament could presumably be administered conditionally.