After reading this it sounds like Degassing your mead could help, but im really not sure how that will end up. ON your own head be it if you do this:)
I also found this.
"If using peroxide, do take care. It takes the oxygen out of the SO2. Use too much and it will take oxygen from the wine as well. That will remove all protection and the wine will be undrinkable.
As a guide ....
Test the SO2 level. Then,
For every 10-PPM of sulfite to be removed in 6 gallons of wine, add 4.2 ml of hydrogen peroxide (get it from a drug store). Use a new bottle of 3% USP-grade hydrogen peroxide. Measure it out very carefully so you use exactly the right amount. Leave for a day before re-testing.
Bob1 .... would it be possible to lower the SO2 just a bit and then use a high-tolerance yeast? Peroxide scares me."
The only problem is this is with wine making. the concepts are the same and PMeta is a powerful antioxidant so it should protect your mead from most oxidization issues. As i understand it the PMeta bonds with disolved oxygen and forms SO2, so any unbonded PMeta should bond with any new oxygen you introduce with the degassing. IF you can get all the Pmeta attached to Oxygen you should be able to drop a large Yeast Pitch and hopefully renew your fermentation.