I know that in the US there are some companies providing this: refillable filters. It works by providing the refillable filters and the buying just the refill of carbon pearls. However, I am not so sure that doing it with a 3d print will translate into a huge impact on reducing pollution. In my opinion, the best solution would be to have companies designing filters in a way that they could be easily opened, so we could dispose of the material separately, and the outside plastic could be easily recycled.

To Reactivate ionechangers and active charcoal in your old filters I use vinegar( 2Tsps) or citric acid and add simple table salt(half a cup) filter that mix with water, let it filtrate, fill and filter twice with water only to remove residues.