My pregame routine when I'm playing versus when I'm not playing is pretty similar. I try to keep it as close as I can so if I do have to go in I am prepared to play. Coaches usually give me a day's or two notice when I'm going to make a start so I can mentally prepare myself in practices leading up the game. I focus on my tendencies with the opposing team and try to solidify those adjustments in morning skate the day of the game.
The only main difference is that I have to eat a little differently. When I'm not playing I don't burn as many calories so I watch more of what I eat. I have to eat a little lighter on the games I'm not playing but, that's the only difference in my routine.