In addition to washing your doona, you should air it out at least twice a year to keep it smelling fresh. Now that the weather's warming up again, this is the perfect time to do it.
You may have already started spring cleaning, so don't forget to add line drying your doona to your list. You can also do the same for other bulky bedding -- like blankets and quilts. If you live somewhere warm enough that you'll pack your doona away soon, air it out just beforehand so that it doesn't get musty while in storage. You should also wash and line dry your comforter when you pull it out again next year.
Take It Outside: 8 Spring Cleaning Projects That Are So Much Easier Outdoors [Apartment Therapy]