Don't drop the long run, and especially don't drop the tempo run.
There's an obvious next step for improved fitness: increased your running to 6 days/week and try to work up to 30-35 mpw. That's the low-hanging fruit and the biggest bang for your buck. All it takes is one more easy run and another few miles tacked on to the other days.
The next step is to introduce intervals. 5 x 1000m is a good place to end up, but not where you want to start. If you haven't done interval workouts before or it's been a long time, start with something manageable like 8-12 x 400 at 1:35 each or 6:20/mile pace. Gradually increase the length of the intervals each week or two while maintaining effort. Don't get injured.
If you can't fit a long run, tempo run and interval workout in your schedule each week or you need more recovery, do two of the three each week. If you're getting closer to a race, the long run is the lowest priority.