You can either reset all settings (including the fan respin period) by pressing "Reset Preferences" in the Configure screen, or change the value of respin period directly in registry under:
HKEY_CURRENT_USER\Software\HWiNFO32\Sensors\FanCtrlRespinPeriod
or
HKEY_CURRENT_USER\Software\HWiNFO64\Sensors\FanCtrlRespinPeriod