Each time a ship is destroyed it will lose durability. If a ship reaches 0 durability it must be repaired before it can be fielded in battle again. Ships are repaired by paying credits.
Note: Premium ships do not require repair.
Your ship is equipped with missile and ammunition cartridges. After a match, if you have flown that ship in it, its missile and ammunition cartridges must be replaced for a small credit cost. This is most easily done by checking the "Auto-rearm" box in the ship fitting screen.