So I'm playing wipeout 2048 on my vita a few days ago (which I'm over 30 hours into btw) when I get a popup telling me the application has expired and I can no longer play it. I figure out that it is my playstation plus account that has expired even though I got no message or notification of any kind to warn me of this. So I renew my ps plus account and go back to play wipeout but the online pass no longer works and I still can't play the game. Then I delete the game and redownload it, just like I've done plenty of times on ps3, so that I can play online only to discover that my save data has been completely deleted. Apparently, unlike ps3, your saved game data is tied to the game itself so without backing up the save, deleting the game to free up memory card space also deletes your save games.
It did warn me that game data would be deleted when I went to delete it; however I just thought there was no way it could mean my saved games. I learned the hard way so this is just a heads up to people who don't know.
