ip http secure-session soft-timeout

This command configures the soft timeout for secure HTTP sessions in minutes. Configuring this value to zero will give an infinite soft-timeout. When this timeout expires, the user is forced to reauthenticate. This timer begins on initiation of the web session and is restarted with each access to the switch. The secure-session soft-timeout can not be set to zero (infinite).

Default 5
Format ip http secure-session soft-timeout 1-60
Mode Privileged EXEC