Here's my advice.
Stay between 45 and 50 and stay CONSISTENT.
Do a longer run each week (this really helped me). Also, on race days try and get some more mileage in. 2 warm up, 1 race, 3-4 cool down. Etc.
Make sure to do your strides, form drills, and core.
If you do all that you could be down to low 4:20s high 4(teens). If you try to run 60-70 you will most likely get injured. But who knows what will happen.
The best way to get better is through progression, not huge jumps in volume. And getting injured sucks. You'll be much happier if you run 4:25 not 4:19, than you will be if you get hurt.
Cheers.