Filters are not reusable. After they reach their end of life, it's time to chuck them and get a new one.

The housings and cartridges that filters go in are reusable.

For example, the DI Canister will need fresh resin periodically, but you can keep using the same DI Canister over and over. If you don't want to deal with refills, then you can toss the canister and just buy a fresh one every time.