Yes. It can be done, and it’s RELATIVELY straightforward as far as reprocessing goes, but it’s rarely worth the effort and expense involved; in many cases it’s both easier and less expensive to just pop in a new tube. For the most part, tubes on CO2 lasers are regarded as a consumable.
RF excited and medical tubes are done all the time. I've pumped one DC tube myself, but I do not have Xenon and Carbon Monoxide on station, so lifetime was short.