I am community college runner. My freshman season I ran a 5:35 1500, but now that my sophomore track season is about to start, do I have to change my running schedule drastically to run a 4:45 1500? because that's my goal. Thanks.
Here's the short answer, yes.
Now for the long answer. I only saw a dramatic drop in my 1600 meter time from my junior year to my senior year in high school, but then it wasn't a huge drop. I think I went from 4:50 to about the high 4:20's. The reason for the drop was not from in season training, but from training out of the season. I came into the season in better shape, and my times got faster and faster.
Once I was in college, I never saw a huge chunk of time come off because I was running pretty consistently. Maybe if you aren't running a bunch in the off-season, you can reach this goal, but if you are already pretty serious about your training, and you were the previous year, it might not happen for you.
One thing about running is you can always do more. You can eat real healthy, work on your running form, lift weights, work on your core, develop speed, increase mileage, and in the case of the professionals, live to run.
Here's a video on race strategy for the 1500 meter run. It's titled 1 mile race tips, but this applies for the 1 mile, 1600, and the 1500 meter run.
I hope this gives you a picture of what can be done, and what is realistic for you. I wish you the best of luck. Hopefully, you ran that time without a lot of training. Then you have a decent shot of achieving this goal.