The problem is I need to buy a purchased app again.
I think "itch.io is a one-time purchase store", "itch users do not have to pay extra, if the app becomes expensive" and "Users can download indefinitely".
So I think, Now that the app has been updated, You have to allow me to download this without additional payment.
As a response, What about "Make the latest version available for download from the development version user's DL page", "email the DL link to users"? Please consider that.
By the way, Where is your email address? I searched but couldn't find it. Thank you.