The only way to get better at something is practice. If you want to be a better runner, you've got to do running workouts, but you also need to strength train. I'm not saying you have to become a bodybuilder, but you do need a strength foundation to prevent injury and improve your strength endurance and speed.
By incorporating one to two strength training sessions a week into your current running program, you're bound to see an improvement in your performance. If you haven't started training for your next race, I highly recommend following this four-week workout plan to build a strength foundation.
Now, it's time to switch gears and strengthen your muscles.
Before you get started with the workout, be sure to activate your glutes and your abdominal muscles (don't forget to do these drills before your runs). This workout is broken up into three different portions. You'll start with plyometric exercises that will help with reaction time to the ground, which translates to explosive power, speed, and force production. After that, you'll take two minutes of rest, then transition to the strength exercises. The rep and set scheme is for strength endurance, which you'll need to get through speed workouts, long-distance workouts, and race day. Don't forget to cool down after the workout.
Take two minutes of rest and then continue with the rest of the workout.
If this is too easy, you can perform this exercise with dumbbells.