if I'm using a different client other than Bitcoin? I had Bitcoin lte installed previously, but now I'm using cgminer. Does that mean the app-data folder isn't necessary?
CGMiner is not the bitcoin client. It's a mining client, which allows you to connect to a pool and mine for bitcoins. There's a few more clients apart from the Bitcoin-qt client (downloaded from bitcoin.org) like Electrum, but it's a good practice to back up the wallet.dat file in appdata\bitcoin before deleting anything as that contains your coins.