Going into application settings and then clearing data for wallet is the same as resetting wallet from within the application, without having to enter a pin. Know what that means? You're able to set up a new password and have access to your prepaid card.
That's right. If a tech-savvy thief has your phone and you don't have a passcode on the lockscreen (possibly because Google's implementation of passcode stuff sucks) or the screen hasn't timed out yet, the thief will have access to whatever funds remain on your Google prepaid card, regardless of the pin you set in the application.
This is yet another reason why Google needs to add the ability to lock out INDIVIDUAL applications with a code or face recognition, not just the friggin' lockscreen. If someone gets your phone after you've entered your lockscreen code/pattern, they have free reign over the device as long as the screen is on. Third party software for this purpose just doesn't work very well at this stage. This functionality needs to be integrated into the OS. Sorry for going off on a tangent.
1) Go into application settings
2) Clear data for Google wallet
3) Open wallet and set it back up
4) Everything remaining on your Google prepaid card can now be used.