I wasn't sure they were designed to be reused. But if it's cloth and not pressed felt, they should be cleanable. Try it on one and if it turns into soggy dryer lint you'll know that they're a one shot deal.
Gonna be a messy operation though; not something I'd run through the family Maytag. Let the bags drain as completely as possible by turning them inside out over a drain container. Trick is then to rinse the bag by flowing cleaning solution (solvent, detergent, whatever?) through the felt from the cleaned oil side to the contaminated. That'll drive the sludge out without pushing it further into the cloth material. And of course, dispose of the sludge properly.
Good luck.