Shake your polyester comforter out every few weeks. Hold one edge in your hands and lift the loose end into the air before bringing it back down sharply. This snap redistributes the polyester filling and also shakes away any dust.
Hang your polyester comforter over a outdoor clothesline and beat it with a carpet beater. This allows the comforter to fluff up while also getting rid of any dust, debris or crumbs that are on the comforter.
Place the comforter in a dryer with two or three tennis balls and send it through on the lowest heat cycle. This freshens your comforter as it fluffs it out. While a home dryer works well for a comforter sized for a twin or a full bed, you may need to go to a professional laundromat for one that can hold a larger comforter.
Rotate your comforter on your bed every day or every other day. This helps keep the batting inside the comforter even.