An MEP/IR can only be revalidated if the rating is still within the 12 months of currency. Outwith 12 months, the rating has to be renewed and must be done in the aircraft itself. Revalidations of the MEP/IR in a sim(FNPT etc) can only be carried out on alternate years....ie. every second year.
As far as Type ratings go.....a valid(and current!) MEP/IR is only required for an initial Type Rating.
I am of course speaking JAA land here too.