The opportunity should always be open for those who repent to come to God. God makes the decisions of who is in the covenant, we typically do not. There are times, of course, when it is given to those in authority to make decisions about the official status of a person in the eyes of the covenant community. While the Book of Mormon text does not discuss this particular administrative option, it is the power of excommunication held by the leadership of the church.
“Excommunication is the most severe form of discipline or penalty that can presently be imposed by a Church court. It consists in severing the person from his Church ties so that he can no longer be considered a member of the Church. If the excommunicant subsequently repents, proves to be faithful, and is found qualified and worthy by the appropriate Church authorities, he may be readmitted to the Church through baptism. Following further testing and proven faithfulness, the former blessings of the readmitted member may also be restored. Excommunication differs from disfellowshipment in its severity and in the steps that must be followed before the person can again become a member of the Church in good standing.” (Daniel H. Ludlow, A Companion to Your Study of the New Testament: The Four Gospels [Salt Lake City: Deseret Book Co., 1982], 86.)