A lot depends on whether you have gotten bigger and stronger, what your other prs are and how committed and how badly you want it. I think if you did something similar to what I have done you could get it with a lot of hard work. How many miles a week did it take to get to 4:47 and how long did you have to train to get back to 4:51. My freshman year I ran 4:55 and 2:13 on 25-30mpw and started training in mid-February. My sophomore year I ran 3 weeks of base training starting a week earlier than freshman year and probably averaged 45mpw the first 3 weeks and then averaged 30-40 for the rest of the season (still taking 1 day off per week). My sophomore prs improved to 4:40 and 2:06. I continued on and decided to do summer track where I ran 4:16, so I probably improved to a 4:35 1600. Now this is what I did my junior year (this past year):
I prd this year with 4:22.5 and 1:56.5
-started the last week of December- 30 miles
-January- averaged between 35 and 40mpw and began to incorporate a 5 mile tempo in early January (only started out at 33 minutes for it which is really slow)
-Febuary- averaged at least 40mpw with a tempo and then started doing track workouts 1-2 times a week by February 15th (these included 4x1200 with 4 minute rest in between, 6x1000's with 2:30-3:00 minutes recovery) I also got my tempo run down to 28:20 right before the season started (late Feb/early march)
The typical training week for me in January and February was:
mon: 6miles 43:30
tues: 6miles 43:00
wed: 5 mile tempo run (on the road until late feb)
thurs: 7miles 50:30
fri: off
sat: 7miles 50:00
sun: long run 12-14miles (usually 12, my long run got progressively faster as the season went on. I started at 7:40's for 12 miles and by early april I did one as fast as 6:30 pace)
Key track workouts that I completed throughout the season:
middle of March: 10x400's in 66.7 with 1 minute recovery (extremely hard), 8x800's with 2 minutes recovery all under 2:30 (moderate)
late March early April: 4x1200's with 4 minute recovery (3 minutes of jogging slow, 1 of walking) got this down from 3:45/rep in late feb/early march down to 3:36 average in early April, 6x800's in 2:25avg with 2:30-2:45 recovery
mid-late april: 6x800's with 2:45rest in 2:22 average (fairly difficult)
May: 8x1000's (first set relaxed/tempo pace 3:18. 3:16, 3:15, 3:14, 8 minute break, 2:58, 2:57, 3:02, 3:07 (died on the last one) difficult from a volume perspective), 1k cut downs (very common workout) 3:06, 3:04, 3:02, 3:00, 2:58, 2:56 3 minutes recovery)
Results of races throughout the season and why all these workouts were important:
march 15th: 4:41 6th indoor (personally it was a bad race do a time trial 1600m by yourself before the season starts)
march 24th: 1600m time trial 4:40 1st (still unhappy and believed I was in better shape than that)
april 19th: 4:34 2nd (bad weather conditions (sub 4:30 effort)
may 3rd: 4:35 2nd, bad race but I had improved my speed at this point running 2:01 for 2nd 30 minutes after the 1600m
may 16: 4:33 2nd died on the last lap (splits were 66, 2:12, 3:18/19 and then 4:33 so a 1:14 last lap)
june 2nd: 800m 1:56.5 I absolutely was flying
june 7th: 4:22.5 1600m I finally had the huge breakthrough I was looking for and this would be a time that you would be happy with OP
Speed workout 8x300's all under 45 with 2 minutes recovery this was my staple speed workout which I did at least 4-5 times during the last month of the season.
Good luck next year and running xc this fall, if you don't already is HUGE for track. I think you can do it or get close, most people improve 10 seconds a year but you were injured so I assume if you were healthy you would have ran 4:37 and then 4:27 this coming year.
The only thing I might change looking back on my training this past year is that I wish I had ran 50-55 miles instead of 40-45 miles for even more improvement.
Good Luck man!