I'm going to echo Indrah on this one. RM is a great tool in its simplicity, and while it can also do a lot of advanced things, many of those generally do require patience, understanding, and knowledge. As Indrah stated:
Tl;dr suck it up. Fixes, mistakes and reuploads are just part of the developer process. Get used to it.
You're in a situation where you must encrypt the data, and as a result applying patches for updates becomes a bit more complicated, not that patches and updates were ever that simple to begin with; but in addition to making sure your update doesn't corrupt current game save files (forcing players into a restart), you now have to figure a way to handle this through an auto patch of sorts (for lack of a better word). The player won't be able to copy and paste the updated files themselves since it's encrypted.
So you're either going to have to figure a way to get this done automatically, but then that means your game will need to be connected through the server somehow, or requiring the player to download the update themselves and ensuring that clicking this patch will auto update all the necessary files, something non-comp savy fellows may have problems with.
There are times when the work involved is not worth the hassle. Most developers and players expect that the demo isn't the final piece and they'll have to restart from the beginning again, unless the demo is just a teaser of an already finished product. It's probably better for you to ensure you have everything finalized in the finished product so you don't have to worry about patches and updates.