Depends on how old the door is and how much wear is on it. When looking at a new door keep in mind that you will get better energy efficiency with a new door, much less possibility of condensation, less air infiltration and better aesthetics. You will also get a 30% tax credit if the new door qualifies. Subtract the tax credit from the price of the door and then look at the difference in price between just replacing the glass as opposed to replacing the entire door.

With a metal frame in Indiana, I would remove the whole unit and get an Andersen door.
Ron

I would not spend the money to rehab an old door unless it was historic.

Not sure that I would specify an Andersen door as a default either.