Here's how you clean a K&N Filter... First, take it out a lay it on the ground.
Make sure you have the right kind of cleaner and oil. I paid about $10 for this and it can be used for several cleanings.
Spray the cleaner into every crack on the filter. Leave it on for 10 minutes...
Rinse well. Do not use high pressure... a simple flush is recommended.
Once the filter is dry, spray on the oil on the "dirty-incoming" side. You may have to make a few passes on the filter. Once it is all red, it's ready to go back in!
It's that simple. I know there are other brands of reusable filters, but I'm not familiar with them. If you have a better product, please feel free to share!