[CLIENT] Patcher is not updating itself to latest version

I recently began playing League on my laptop after not having played on it for a couple months. The old patcher did not automatically update itself to the new hotness, although it still functioned correctly (downloading and installing new patches) and allowed me to log in and play games. I've seen solutions involving uninstalling and reinstalling League to fix this issue, but I'd prefer not to have to do that.

My laptop is running Windows 8.1, in case that has anything to do with this.