Why rewrite? When there's a new major feature release, take the opportunity to change the target framework. Most servers also have a refresh cycle so update tha

Why rewrite? When there's a new major feature release, take the opportunity to change the target framework. Most servers also have a refresh cycle so update that at the time and roll it into the testing procedure. I'm not saying do this immediately after every new IIS / .NET release, but going 9 years without change is risky.