You don't clay a ceramic coating. If you want to "refresh it" then you wash it, dry it, de-tar it, wash it and dry it again then apply a hydrophopic coating like Carpro Reload. Generally the manufacturer of the ceramic coating will have their own equivalent product. My car is coated in Carpro CQuartz Finest Reserve Cold. They also do a product called Essence Plus which goes on like a wax and buffs off. That'll keep you occupied for a wee while.