Fuji is correct. The written is for initial issue only. Once you got it a flight test is all that is repuired to renew. I seem to remember from CAP53 that if you let it lapse by more than 5 years then you have to do trainig as per the CFI's discretion then the retest, but can't confirm this without the doc in front of me. Remember the IMC is a UK rating so in effect CAP53 details on this subject are still correct.