The sacrament of baptism confers on the soul an indelible character. Therefore, this sacrament can only be received once in your life.
In fact, when we die, we speak in an analogous fashion that the soul has the mark of baptism. Confirmation and Holy Orders also leave an indelible mark on the soul and can only be received once in a lifetime. Confession, Holy Eucharist, and anointing of the sick can be received as many times as necessary.
Confession must be received at least once during the Easter season (which starts on Ash Wednesday and ends on Corpus Christi Sunday) if the person is in mortal sin. Daily Communion is encouraged. Anointing of the sick is to be given every time a person is in danger of death, for example, if they are going under anesthesia. Marriage can sometimes be received more than once, but only in the cases of the death of a spouse or the annulment of a marriage.
Some Christians may use the term “rebaptize,” but it is an oxymoron since a valid baptism by nature cannot be repeated. You can only become a child of God once, and it is never undone or lost.
For example, a baby could be born in the hospital and not expected to live. Church law gives anyone the permission to baptize in the case of urgent necessity. As long as real water flows over the skin and the correct Trinitarian formula is spoken, the person is validly baptized. This is called extraordinary baptism. If the baby survives, then she is brought into the Church for what is called “supplying the ceremonies.”
In other words, a new or second baptism is not celebrated, but the other rituals of anointing and profession of creed by parents and godparents are performed to complete the liturgical dimension of the sacrament. The Church record will indicate that baptism occurred on a specific date in the hospital and the ceremonies were supplied on another date in Church.
A similar procedure exists that is referred to as conditional baptism. The formula is similar to regular baptism but the words “I conditionally baptize you” are used by the minister. Conditional baptism is performed when the candidate for the sacraments cannot prove that he was baptized, or if there is substantial doubt as to the validity of his baptism. No document exists. Without the moral certitude and because of the necessity of baptism, conditional baptism is recommended. This might arise after an accident when a person is dying.
Also, some denominations may claim to be Christian but in actuality are not because they do not believe in the doctrine of the Holy Trinity, nor do they use the Trinitarian formula for baptism. In these cases, a candidate to be received into the Catholic Church is to be baptized properly.