Most likely you have to delete the old vTuber Kit data, but I'm not 100% sure. If you want to try, go to the start menu and search "regedit" and the Registry Editor app should pop up. Click on that to open it up. In the window that pops up, on the left side is a bunch of folders. Click Edit at the top and go to Find. Type in "Kyuppin" and hit enter. It should bring up a Kyuppin folder on the left panel, and in there should be a folder called vTuber Kit. If you see a vTuber Kit folder, right click it and delete it. That will clear all saved data and hopefully let the program start. Be careful not to delete anything else in Registry Editor though.