I'm 90% sure national code says soft good should be fireproofed every 5 years. I'm not aware of a code that requires fireproofing for sets and painted surfaces.
However, national code (
NFPA 72) also gives local authority (your fire marshal or city inspector) the right to make any local rules he wants, so you MUST!!!! check with him/her. Beyond CODE concerns there is a manufacturer's tag that tells you how long the original fireproofing is good for, but that doesn't mean that subsequent fireproofing used the same materials or is good for as long. Records of each subsequent treatment should be maintained, including the life expectancy of the treatment.