A foam filter you can do that with a couple of times but are cheap enough to just replace. Paper filter just needs to be replaced if you can't blow it out with air, which can generally be done on a regular basis t help prolong the life of the filter. A K&N you can clean with a good degreaser or even gas and blow dry, however they last (reportedly) 40 to 50K miles before replacement. I run one in my 1200 LTD (Came with it) and it has done well for almost 20K miles so far with no maintenance except being blown out with air a couple of time.. However, nothing last forever and if you don't know the date it was originally installed, I would just replace it. If it starts breaking apart then you could have more issues that it's worth.