Hi CollinCC,
Refresh option? Isn't this a receive data connection? Just go to data connections and click Modify, walk through the wizard and select the new columns. Make sure you don't change the name of the connection towards the end and it won't break the bindings.
If this isn't a secondary data source, I am lost. You can add fields to your form and promote them from the Form Options dialog (under Promoted Properties), but the old forms won't have the data in those columns. At any rate, if you're querying the library to get a list of forms with columns, then that's a receive data connection and the modify should do the trick without causing a bunch of rework.
Good luck!