[debacle]

I think one of the big problems with the app store model is that it creates this idea that you only pay once for software, ever.

Your software doesn't have bit rot, it's just old. It was useful at one point in time and it is just a bit less so now. Consider the value proposition of a Magic Maps 2.0 to your users and what sort of feature list you could create. Decide an upgrade price point, and send an email to your users and create a newsletter allowing them to sign up for the new version. If you get 500 sign ups, cost out the features and have a freelancer develop them. If you get no sign ups, pack it up or sell it to someone.