EFRI Trainer Manual:To maintain the Emergency First Response Instructor rating, individuals must renew their rating every two years by submitting a renewal application to Emergency First Response. Renewal requirements include teaching at least one Emergency First Response course every two years.
The amount f time it's been since your rating has lapsed will determine what action is needed to regain the teaching status. There is an online refresher on the PADI Pro's site (Pro Development, EFR), that is usually enough to regain the rating...