Chemi Pure (which is primarily carbon) cannot e recharged. I'm also not sure I would give it a 4 to 6 month lifespan, as that time period will depend on what is in, or put into your tank. I change the bag (smallest size bag they make) every 8 weeks. I also agree with sperry that the 100 ml bags of Purigen (all you need for a 24g tank) are cheap enough to replace than deal with regenerating them. A 3 pack at F&S is about 16.00 and if you change it every 4 months, that's your entire cost per year. While I do watch out for color changes, I still change out every 12 weeks or so just to be safe. It also allows me to work out close to a fresh bag of either one each month.
I also run a sapphire skimmer and pull out enough brown slop that not even my dog will sniff at. Even with all that, I still maintain weekly 5g water changes on my 24 aquapod. For me, the carbon, purigen, and skimmer are all nice to have, but it doesn't relieve me, at least from still changing the water. I figure if I waste an extra $50.00 a year on the chemical filtration, it beats the cost of crashing my tank because I fell a few days late in changing out some water. Given how much money I've already sunk into this tank, it's worth the few extra bucks, even if I can't prove it has dramatically benefited my livestock.