I'm assuming cross is done for you now?
Take a little time to recover, trust me, you'll thank yourself later on. Could be a few days off, could be a week or two, could be active rest if you enjoy doing other activities. Just make sure that when you get back to running, you're ready to go.
Since you're talking about running 1500m, you need to get really good at running hard for 3 minutes. If you can get 3 minutes in to a 4 minute race and still feel relatively good, you're well positioned to race that last minute.
You can build up to this in a number of ways. The easiest is just to insert some faster segments of 1-3 minutes into your runs. Don't want to use a watch, run hard to the top of each hill. If you're in the flatland, stuff like 1 minute on, 1 minute off x 8-15 is a nice off season quality session. If you love running around the track, maybe do 800s at slightly faster than your threshold pace with an 800m recovery run at easy pace. For a 16 minute 5k guy, maybe the 800s are 2:35 ish. Give yourself until the watch gets to 7 minutes to start your next 800 (so, easy run the next 800 in 4:25 ish). Once again, you're getting some quality without running the engine too hot. If you do 5 reps, you'll have a 5 mile run in 35 minutes with 2.5 of it at around your 5k pace and the whole session won't be that hard.
The other thing you need to do is to improve your threshold. From your 800/1500 time, it seems like you're probably already pretty aerobically strong, so I'm guessing that tempo runs and threshold runs are something you have done quite a bit of. Once a week, do an out and back run where you run out easy for 20-30 minutes and then try to come back 10-15% faster. So, if you run out easy at 7:00 pace, for 30 minutes (about 4.25 miles), turn around and come back in 26-27 minutes (about 6 min per mile). Doing it this way is kind of mentally easier than saying, I'm going to run this 5 mile loop at x amount of time.
At least once a week you need to sprint (as in full go, full recovery reps). We do this on the day before our tempo efforts. It's an aerobically easy day for us. We'll run 30 ish minutes easy, then go through an extensive series of drills and easy build up sprints, then we'll do something like 3-4 x 60m full go with 4-5 min recovery OR 2-3 x 150 full go with 4-5 min recovery (the longer reps can sometimes interfere with your quality workout the next day, so don't do too many). We do weights on this day as well.
The other days of the week, fill it in with as much mileage as you can handle. If you were a 42 mpw guy, try going up to the high 40s, You're already doing pretty good, so don't feel like you need to go crazy with the mileage.
Maybe sprinkle in some strides after your hard runs and you're probably golden. A week for you might look something like this
M: 6 mile run with 10 x 1 on 1 off inserted, with the ons at 5:30 ish pace and the offs at your normal easy pace (don't run the ons so hard that you need to totally jog on the offs. Strides after
T: 7 miles easy
W: 4 miles + drills + sprints + weights
Th: 8 miles (4 easy, 4 fast) +strides
F: 5 easy + weights
S: 9 easy with occasional accelerations to around 1500-3000 race pace for 20 seconds during the last few miles
S: Off or easy 3 mile shake out
This would get you to your previous peak of 42. As you get fitter, you can add a mile here and a mile there and build toward the high 40s.
Do that for the next 4-6 ish weeks and then you can try moving on to tougher stuff.
As you get stronger: The reps should become FASTER and the tempo stuff should become LONGER. The good guys around here (8:5x through 9:1x for 3200) were going 7 miles tempo on the track at 5:30 pace last year