Shake and fluff a duvet every morning after use. This will help to keep the feathers or other fill evenly distributed. If you keep a duvet cover on the duvet, you'll rarely need to clean the duvet itself. You should wash the cover as often as you change your sheets. It's usually recommended that when necessary, you wash your duvet in a large commercial washing machine. Chemicals in dry cleaning can break down the fibers of the fill. Dry a duvet using the gentle heat setting on the dryer. When it's partially dry, take it out, give it a good shake to break up damp clusters of filling, and finish the drying. Hang a duvet out to air dry for at least 24 hours to make certain all sections are dry before replacing on the bed. If you keep the duvet inside a duvet cover, it will stay clean and fresh for months.