There is no limit, unless imposed by specification, for the number of PWHT's imposed on a weld joint. That being said there should be some practical limit. The number of times for PWHT is not such an issue as the time at soak temp.
Since your first PWHT was rather low this works for you. The idea to higher temps is to reduce hardness.
Most of what happens in PWHT actually happens in the first couple of hours. After that the rate of change slows down considerably. The first two hours or so depends predominantly on stress relief through a creep mechanism and is responsible for the precipitous change in mechanicals. Once this process runs it course for the most part change in mechanicals depends more on carbide precipitation which is diffusion controlled and by definition much slower. In many cases after 6,7, 8 hours or so the PWHT curves become quite flat. Meaning things don't change very fast.
Verification of such can be garnered from ASME Section IX wherein time at temp is considered a supplementary variable related to impact testing regimes.

One potential problem with multiple PWHT cycles, is that if you have CVN testing requirements, you probably exceeded the 80% rule for qualfying PWHT on your PQR for the welds in question.