Maybe the question should have been phrased: does an MECIR renewal also renew the PIFR(SE)? That's it, just what the rules say is what I was having difficulty finding.
I requested the ATO to do that at a CIR renewal. He duly signed off the PIFR in the AFR section of my log book but I rather got the feeling he did not like doing it. I think he was a bit disdainful of the PIFR generally. I don't think you have to ever 'renew' the PIFR. It's just an AFR with a qualified person and so your ATO can sign that off when you renew the CIR, if they so choose.