I assume you're UK flag. Book out of Gouvia, telling them your next destination is (presumably) Albania or Italy - wherever. They'll stamp your 60 entry DEKRA, hand it back to you, and they won't expect to see you again until you book back into Greece in a couple of years time . . . if at all . . . when (current practice) your DEKRA will still be valid.

Don't forget Q flags and immigration when you're entering any EU port from a non-EU country!