What you could do is use a trigger to detect it a player leaves, setting a boolean variable, EG:
Player_Left_Game(index) = true
You could then use your periodic check to see if that variable is true. If you don't want to pick-up the same player over and over, use another boolean variable, EG:
Player_Leaving_Done(index) = true. Then when you look through your list of players, just check the "Player_Left_Game" variable, if true, then check the "Player_Leaving_Done" variable, if that's false, then set it to true and do the rest of your actions.
Hope I've enlightened...