Yes they can be repaired but it is not inexpensive. You are in a good place (WA/OR area) with many options for getting that kind of work done.
County Coach Corp. and Premier, both in Junction City, OR are examples. I had a similar crack in my driver side near the slide. It runs from the corner of the slide frame down to the beltline. A local body shop (someone I know and trust) gave me an estimate of $1,500 to reglass and repaint. However, he could not guarantee it would not crack again since he felt (and I agree) that it was due to some flexing at that point. So, I covered the crack with some Eternabond tape and put a polished stainless louver over it and it looks like a vent. Cost me about $30. Unfortunately, that likely won't work in your case.
'07 Country Coach Allure 470 Siskiyou Summit #31578, Cummins ISL 425; 2014 Ford F150 toad; Air Force One Toad Brake.
Glen Allen, VA; Smith Mountain Lake, VA.