On properties less than 25 years old
you can usually get away with re-using if installed correctly because at this
time builders started using pre-painted steel which is a very long lasting
product. Check with your roofing provider to make sure it is re-caulked and
re-painted.
On properties 25 years and older,
ideally it is a very good idea and recommended to replace. They used to use a
type of galvanized metal which does not last very long under harsh weather
conditions on your roof, creating rust outs in critical areas.