You can not reassign a user access pass to another user within 7 days. If there were no quarantine period then it would be possible to reassign them on the fly. The number of tokens needed would be very small and Qlik wouldn't be able to afford to sell Qlik Sense anymore or the tokens would have to become very expensive.
If you need more flexibility then turn some user tokens into login access tokens. One token can be used as one user access pass or 10 login access passes.