After a short warm-up, try 30 minutes of one of these workouts.
Intervals: Do a 3:1 ratio of hard intervals/recovery. Try three minutes fast, 60 seconds recovery.
Fartlek (speed play): Replicate a familiar running course using all the different forms for climbing hills, racing other runners or jumping over curbs.
Progressive speed: Count your cadence for 15 seconds. Then run for three minutes. Each minute, increase your cadence by one or two strides. Rest for one minute and repeat.