When I read your OP it appeared to me that you were an instructor. As a DM our shop required me to re-certify either with PADI's EFR or somewhere else that's recognized. I believe I could've taken the EFR Instructor Course and could have satisfied any requirements by PADI or the shop by simply teaching it to one person each year. But, as you are not a pro my (rather odd) advice would be:
Just study your manual and any other materials from your original course regularly (I still read a page most days). Having taken CPR 4 times, I have noticed that very little changes (and sometimes question those odd changes myself). I also noticed that in all 4 courses, it seems to be a breeze and everyone passes. The written "tests" were done orally in one case, and marks ignored in another. What I'm saying is IMO it is more important to review the stuff regularly on your own rather than find and pay for a course--unless someone requires it.