It is important not to have them on a solid thing- like a cookie sheet. Rubberguy is right on target. If you have a perforated microwave plate, you could give this a tryal and error. I have never done this, but I use the microwave to freshen bread and cake. (about 10 sec on high with 1100 watts works for me.)
There are two important questions to ask before engaging in this activity
1. What kind of donuts are they? Filled ones can be problematic.
2. Why are they soggy?
Please recall that there are no calories in the holes!
JayR