ATPL exams use to valid for 7 years from the date of expiry of your most recent IR rating...
So for someone with a JAR CPL and IR (A) who flew using a FAA IR for example (and let their JAR IR expire) their exams would be kept valid by this ICAO IR even though it wasn't JAR.
Provided you actually had a JAR CPL & IR issued, the exams expiring wouldn't require you to do anything to renew the CPL as such, as that licence was issued. You'd have needed to renew the IR exams to at least get that up and running again, and if you wanted to get the ATPL eventually it made sense to just redo them all.
The problem you have though of course is you sat JAR exams, and now it's all EASA- so all what I've said above might be totally useless
