Well I'm far from expert, but I would say train fast to run fast.
Your long run (whatever the run is where you're pushing your distance - no matter how few or how many miles - that's your long run) should be considerably slower than your race pace, an easy jog. But your long run happens once a week at most. Some people now are training on a 10- to 14-day cycle.
Intervals are the gold standard for getting faster. Anywhere from 30 second sprints to mile repeats - rest intervals between repeats should be no more than 5 minutes or double the length of the repeat, whichever is shorter; one thing you can do to progress your interval sessions is to decrease the rest intervals.
Your third key workout is a tempo run. Different people define that differently, but generally it means a mid-length run at a pretty hard pace. It could be half race distance at target race pace, just for example.
The fourth component to getting faster is RECOVERY. Workouts tear down your muscles and stimulate them to grow; recovery days are when you're actually building new fibers. Jog short and easy; take an easy bike ride; do yoga or Pilates or something like that. Take at least one day a week for complete rest.
Then there's just experience, learning how to pace yourself at any given distance. I don't know if you can really gain that except by racing.
That's how I've been getting faster little by little. But jess is right. You're no slouch as it is!
Speed comes from what you put behind you. - Judi Ketteler