First the life stated is for the cell in air...........OF COURSE exposing it to higher PO2's will shorten it's life. BUT nothing will lengthen it's life, or prevent it from dying at whenever the company says is its life (+or-).
Lowvis: If what your saying is that removing the O2 stops the reaction then why not place it in argon each time after analyzing a couple of tanks. If only exposed to say 36% for a few minutes then placed in argon the sensor should last indefinitely.
So take two sensors, use both, place one in argon the other leave in air, do this and see how far apart the die.
John