My team and support a large number of legacy applications all of which are currently functional but problematic to support and maintain. They all depend on code that the compiler manufacture has officially no support for.
So the question is should we leave the code as is, and risk a new compiler breaking our code, or should we bite the bullet and update all the code?
The answer is totally dependant on the resources your employer (or yourself) can afford to make the refactoring (or even totally rewrite big parts).
So you should first estimate how much time/developers you can afford to refactoring the application, then see if you think it'll be enough.
If you can afford time and people, then do it, don't hesitate! You're investing in the future by reducing the time to debug the application so it will be helpful and less expensive once the refactoring is done.