Here's the third week in the progression.
Short Intervals: 10-12 x 200m; 90" rest
Long Intervals: 4-5 x 800m; 2'30" rest
Tempo: 5 miles @ 85% of your 5km pace
As you can see, each week we're adding in more intervals, decreasing the rest, or both. Feel free to adjust these to how you're feeling, with the longterm goal always being progression. That progression can be measured in greater amounts of work (more intervals, longer distances), faster times, or decreased rest. You should probably only change one of these variables at a time.
And again, if you're feeling really comfortable at your short interval distances, maybe focus on the longer intervals (or vice versa). The focus is on high-intensity intervals! Longer runs are good for practicing your pacing, but what's going to make you faster is the intervals.
One thing that I would encourage you to try is to take the goal of the workout and adapt it to your interests to keep it fun. For example, even though I have a track literally next door to my house, I really would rather be running on the trail. So instead of doing 10 short interval 200m sprints on the track, I could use my goal 200m time of 30 seconds instead of the distance as my interval. So my whole workout would look like this:
A. Dynamic warmup: arm swing/pigs-on-iceskates, shoulder pistons, wrist circles, leg swings, lunges
B. Drills: 2-3 x 10-20 reps of 2-3 drills (running in place lean-to acceleration, exaggerated one-legged pull, wall drill, etc-whatever I'm feeling worst at)
C. Run 5-15 minutes, gradually increasing cadence from 90 to race pace
D. 10 x 30" intervals at max effort OR some cadence over my race cadence (102 for example). 90" active rest between intervals (walking!)
E. Run back to my car at race cadence or slightly below.
All told, this would take up to an hour, depending on how much skill work I felt like doing. It's important to get that high-quality technical stuff done in the beginning. And remember, hammer the intervals, but keep them close to each other in distance or time. The intervals ARE the workout. Everything else is just practice.