There are a number of 802.1x client reauthentication options.
You can configure the device to periodically reauthenticate clients connected to 802.1x-enabled interfaces. When periodic reauthentication is enabled using the dot1x reauthentication command, the device reauthenticates the clients every 3,600 seconds by default. The dot1x timeout re-authperiod command resets the reauthentication interval, which takes precedence over the default interval.
When periodic reauthentication is enabled, the device reauthenticates clients connected to an 802.1X-enabled interface every 3,600 seconds (or the time specified by the dot1x timeout re-authperiod command) by default. You can also manually reauthenticate clients connected to a specific port using the dot1x reauthenticate command in the privileged EXEC mode.
If the device is unable to authenticate the client, the device waits for a specified amount of time before trying again. The amount of time the device remains idle between a failed authentication and a reauthentication attempt is specified with the dot1x timeout quiet-period command.