Data lost on update? How do customers update?

Data lost on update? How do customers update?

When an update to an application is available, will the data for your current application be deleted upon update, or will it persist into the new version? I tried it on my own and the data seemed to be deleted. If I had an application that a customer had paid for with the promise of free updates, how would I allow them to update without deleting their data? How can developers update applications for customers?