Speed Workouts. Week 1 speed workout: Warm-up for 20 minutes. Then run 10 by 1 minute hard, 1 minute easy. Cool-down for 20 minutes. Week 2 speed workout: Warm-up for 20 minutes. Then run 2 by 10 minutes at a comfortable hard pace. Rest for 90 seconds in between. Cool-down for 20 minutes.
For a specific piece of advice, try moving your long run from 5 miles to 8 miles, then to 10 miles, at your 8:30 pace. Do this once a week for a month or two, and then go back and put in a 5 mile attempt at, say, 7:15 pace and see if it feels easier. The jump from 7:30 to 7 is big. Go at it in smaller increments. Run more.
UNB6.