Cheerleading is not known to be an endurance event, it actually consist of short periods of high aerobic activity. Fast paced routines requiring strength are what a cheerleader will experience and therefore should train towards that goal. Below are some tips that can help you get a good base of endurance that will make your cheerleading experience much easier.
Of course running is thought of as the best way to get fit, and yes it is good, but try some other exercises that will get your heart rate up in a shorter amount of time. Jumping rope is outstanding for this and you can cut your workout time down using the jump rope. A little high speed jump roping will elevate your heart rate and give you an excellent workout in a shorter period of time.
As far as running goes try a short, slow run just to warm up. Next do short sprints which will make for a great workout to build your endurance. There are a number of ways you can utilize sprints. Pick a distance you want to run, sprint to the end and jog back to your starting point then repeat. You can even walk back if it's a short distance. If you have a track to run on, sprint half the distance then jog the reminder.
There are just a couple examples for improving your endurance and you can use your imagination to expand on these. A good thing about jumping rope or doing sprints is you can reduce your exercise time avoiding a marathon workout. You probably are already very busy and you can save yourself some valuable time.