Construct 2 has a "time" System Expression which is NOT reset when changing layouts and represents the number of seconds since the game loaded, so it would work between layouts put wouldn't persist if you leave the game.
I'm not sure there's an expression to get the actual time in Construct 2, but you could call a php and check the server time to get it. Thus you could store server timein a Webstorage object when closing the session and compare with server time next time you load the game. While the game is running I would use the time object, though, to minimize server traffic.