So far I've seen developers do this, they just release it as a new app on the App Store and then you get to buy it all over again. If you don't feel like you ne

So far I've seen developers do this, they just release it as a new app on the App Store and then you get to buy it all over again. If you don't feel like you need it you can stick to the old version you bought before until you have incentive enough to upgrade. They usually start out at a slightly lower "upgrade" price for the first month or two and then crank it up to the full price. I realise it's really not the ideal situation but if you really need it for revenue it is possible. You can easily add a mechanism to the old version that nudges people about the upgrade.