When your certificate has or is due to expire you can recertify by completing a recertification/refresher course.
I&M (3361) – recertified by SP3361R, SP3351, ND3361 or FC3361
D&E (3321) – recertified by SP3351 or SP3321
GL5555 – recertified by GL5555R
SPUCI – recertified by SPUCIR
All other courses are refreshed by retaking the same course as they do not have separate recertification courses (they are updated regularly with new content)
If you take your recertification course before your original has expired, your new certificate will be dated from the completion date of the recertification course.