Strength training will definately help with the running. There are many programs developed for runners of all distances. You can check the net for lots of free ones and develope your own but would recommend getting some help from a trainer or seasoned runner. At 17 yrs old I assume your still in high school?? Where's your track coach and why doesn't he/she have a training program for you??? Ask your coach to help you with that and if he/she is not willing, then maybe look into a local running club or running shoe store where there are always knowledgeable folks working who love to run. I dont know of any runners who dont use some type of strength training to improve speed and endurance. I believe your old enough to benefit from further training so get a program and start knocking some seconds off that PR. Good luck and good running!!!
Great advice from Dobrobuck and I totally agree with all the suggestions. I utilize weight training three times per week and it has been beneficial with improving upper body strength and better conditioning all muscle groups. Perhaps pay closer attention to your abdominal area because that will really help you out in any long, uphill climbs.