Be careful of the words 'renewal' and 'revalidation'. They are 2 entirely separate events, requiring different actions.
If you 'revalidate' your class rating before it lapses (any time in the 3 months before expiry) then you can do so 'by experience' OR by flight check (LPC).
If your class rating lapses, even by one day, you can only 'renew' it by flight test (LST) with a JAA examiner.
Back to 'revalidation' by experience: this requires the one hour dual flight with an FI who will sign your logbook if the flight with you was safe. IN ADDITION you must find a JAA examiner who will check your logbook for this dual flight together with the other experience requirements and who will then get you to fill in a LST/LPC form for him to sent to the Belgrano and who will finally sign your licence to revalidate your class rating.