simer,
Well, basically if your Flight Instructor license expires you have to do the entire check-ride all over again. Oral and flight, on top of that, I do belive you need a sign-off from a "191"-instructor (2 years experience Part 61, or 200hrs as a 141-instructor teaching CFIs). I guess you could do it in Europe if you can track down a FAA Designated Pilot Examiner authorized to give CFI check-rides.
Good luck!