Q. 1. If the priest runs out of Consecrated Hosts during Holy Mass, can he consecrate some more Hosts, either by saying certain prayers or celebrating the minimum requirements for a Mass within a Mass?
A. 1. The universal liturgical order of the Holy Mass can only be changed by the Vatican. No priest has the authority to change the order of the Holy Mass by adding, changing or removing the liturgy of the Holy Mass.
On this matter, the Code of Canon Law states:
Can. 838 §1. "The direction of the sacred liturgy depends solely on the authority of the Church which resides in the Apostolic See and, according to the norm of law, the diocesan bishop."
§2. It is for the Apostolic See to order the sacred liturgy of the universal Church, publish liturgical books and review their translations in vernacular languages, and exercise vigilance that liturgical regulations are observed faithfully everywhere.
The proper procedure, when the priest determines that he will run out of Consecrated Hosts, it to break up the remaining Hosts and give everyone a part of a Host. According to the teachings of the Church, the fullness of the Real Presence of Jesus is in every piece of Hosts, no matter how small and equally in the Consecrated Wine. As such, it is not necessary for the faithful to receive both, the Body and the Body of Christ; One is sufficient.
Furthermore, the Code of Canon Law states:
Can. 927 "It is absolutely forbidden, even in extreme urgent necessity, to consecrate one matter without the other or even both outside the eucharistic celebration."