Which smartcard are you using for authentication.
I am not sure that it is possiable since the smartcard is used only during the authentication phase only and when a new session key is created.
On the concentrator you can adjust the re-keying parameters so key will be created in shorter times.
Each key creation requires the smartcard to be plugged in and if removed the vpn tunnel will no longer exist.
Regards.
Yossi Mor