Your post is quite confusing, at the start it sounds like you are saying letting the exam period lapse and not getting an IR, at the end it sounds like you are saying let an IR lapse.
You have 36 months from the date of the last ATPL to submit the paperwork for a CPL and IR. If you do not meet this requirement you will have to retake all 14 written exams. Any training required for this will be at the discretion of the head of training at an FTO (ie you do not have to redo a whole course), however anyone who thinks this in an easy option is fooling themselves. If you can just go ahead and retake all 14 exams over 3 years after you last looked at the subjects without significant time and effort studying, you are being unrealistic.
Once you have the IR you can let it lapse for up to 7 years before you have to retake the written exams. Once lapsed the renewal is basically the same as a revalidation, so no real hardship and shouldn't cost too much if you shop around and can get in a sim cheap/free to practice.
Last edited by RTN11; 16th July 2012 at 17:18.