I just ran a 5K on a VERY hilly course (the track runners I talked to said it was the hilliest course they'd ever run) and got a new
PR, even on that course. My strategy was to turn up the resistance on the elliptical and go as fast as I could for the last 10 minutes of my workout and to run outside (a little bit of hill) as opposed to the treadmill as much as possible.
On the day of the race, be willing to drop your speed on the way up the hills (I even had to walk for about 10 steps up one of the hills on my race) and fix your eyes on a spot--NOT the top!--about 10 steps ahead of you, and make yourself focus on getting to that spot. Also, make up the time lost on the uphills by going as fast as you can without falling over on the downhills, working on recovering your breath as you go down. If you lean back and keep your back straight, you can fly down the downhills and make up a lot of time.
Congratulations on winning your age group last time, and good luck on your race!