No need to replace the windows. As Clifftall says, there are several places that will repair the windows. One of them is Suncoast Designers
on the Gulf Coast of Florida. We have used them in the past and were satisfied with the results. You can drive your RV to them and they will remove the windows and repair them, or you can remove the windows yourself and ship them to Suncoast.
There are at least 2 other outfits and at least one company that sells the seal material so you can do it yourself. The info is probably in the threads in the link provided by Clifftall.