Um...Isnt it revalidate up between 3 mon before & up to 5 years after - thereafter its known as a renewal.. .. .
AFAIK - can correct me if I am wrong - but there is little difference between letting it lapse by a a year or two or revalidating earlier - its the same cost with the same flight test and the same form with the same payment isnt it? Other than not being able to fly where an IR is required AFAI can see there is no loss of anything...including ATPL theory (which is 7 years since last date of IR CoT?).. .. .I mention this as my IR lapses on the 28 but am testing on the 29.