The method includes: (a) preparing a liquid cartridge to be recycled and including a liquid storing unit, a liquid delivery path having an opening, a blocking member detachably mounted in the liquid delivery path to block the opening, and a valve configured to be switched between an open state and a closed state; (b) removing the blocking member from the liquid delivery path; (c) switching the valve from the closed state to the open state; (d) injecting liquid into the liquid storing unit through the opening with the blocking member removed in step (b) and the valve maintained in the open state achieved in step (c); (e) switching the valve from the open state to the closed state after performing step (d); and (f) assembling the blocking member or another blocking member different from the blocking member in the liquid delivery path to block the opening after performing step (e).