Probably the biggest thing that can improve team spirit is to have 1 or 2 people on the team who are willing to risk their reputation, go out in front of the team, and start different spirit acts. Whether that means they yell something and the team yells something back, etc. Also, it is an even better idea to have a good dancer on the team to encourage more from the rest of the team.
Other than that, be sure to summon the spirit of team spirit. That may help.
-Joe