Unfortunately, it’s not a DIY fix. Once this happens, there’s really no way to fix it yourself that will last. Plus, any insulating gas like argon is long gone. Your two best options are to have a professional shop handle the repair or just replace the entire window. In many cases, replacing the window ends up being the simpler and more cost-effective route. RV window companies like Lippert or Peninsula Glass (RVWindows.com) should be able to help. Or taking it back to a dealer might be an option. Installation of the new window can be DIY if you’re handy.