I'd like to point something out. After some unfortunate mishaps with my phone while trying to redeem it at Target I stumbled across a major flaw/blessing with the Pokemon Pass app.
None of the data is actually tied to your PTC Account. Not even the Let's Go Codes. I had to reset the app data multiple times because the app would only work once before I had to clear the app data.
If you need more than 3 codes just open up the App Info for Pokemon Pass in the Android System Settings, Clear it, Log Back in, and if your location is still Target you can keep getting Codes.