You won't be able to re-tap the hole, it will need to be fixed.
A heli-coil would be the easiest fix. To do that you need to remove the cover completely, redrill to the larger size required then insert the heli-coil using a bolt and nut in a tap wrench. I usually start the first couple of threads with a taper tap so that it goes in perfectly straight. It will then have a steel thread which should not strip. Replace cover and all bolts using torque wrench.

The only other (and best) alternative is to have the case repaired by a machine shop which requires welding the hole and re-drill / tap to original spec.

Try the heli-coil first would be the best option, good luck!

TBA, Stainless extractors / drag pipes, 65mm over forward controls, Thruxton needles, 904cc, head ported, lowered 1-inch, Console removed, relocated battery box, Australia.