They will be upgraded automatically as your turret/hull level goes up depends on the experience you earn by playing from that specific equipment.
Upgrades are now free, they just upgrade by themselves.
Due to the latest game update, the arms race, turrets and hulls have now only 10 upgrate levels instead of 30 and this level can be increased by the amount of experience you get in battles. They no longer require crystals to be upgrated means that your equipment will upgrate by itself once you reach the amount of experience needed.
Customer support service by UserEcho