Run a regular speed endurance or speed endurance workout right after your time trial. We do this all the time when we don't go to a race. I don't mix speed endurance (400s and longer) with speed (399 and shorter) in my system.
I coach mostly higher level female runners but I coach a few age groupers.
One of them is a 41 year old male who is a cancer survivor and lifetime runner. I've been looking over him since August 2008. He seems near your level because one week ago he lowered his masters pb in 5K from 19:37 to 19:15. His natural talent lies in the 800m and 400m, then 1500m.
This is one of his Tuesday runs when he was unable to run a local all-comers meeting.
1.)10 mins jog barefoot in the grass field with some stretches after.
2.) 10 mins jog barefoot in the track with some stretches when he feels he wants to stretch.
3.) Striders: barefoot in the grass-- runs 4-30 secs striding with 90 secs slower. Then 2 mins more = 10 mins.
He stretches when he needs to. I do not press him. He has problems from cancer and the meds given him such as some permanent muscle damage (now those meds have disclaimers for causing permanent muscle damage).
4.) Time Trial on his own in spikes starting in lane one: 800 metres in 2:26.24. It's his masters pb.
5.) Jogs 2 mins. Then Changes into lightweight trainers. So recovery is about 4 mins total.
6.) Fartlek: He starts from the track and heads out on the roads (and sometimes grass fields) for his speed endurance fartlek but it is very much threshold stuff. His pace is very naturally 6:40 down to 6:20 when he feels good. After this 800TT he ran 4 times 9 mins with one min. jogs. He often carries a water bottle in his hand during this. He does this by how he feels at that moment. This = 40 mins total.
Then he ran back to the track to cooldown in the opposite way he warmed up.
7.)Like #3. 8.) Like #2. 9.)Like #1. 10.)Walk 20 mins barefoot while eating nutritous foods.
We grow up barefoot running here just so you understand that that is our way.
So it was over 100 mins running. He runs by time not kilometres.
So if you fit my system of training then I would have you do something like this. Also we run speed/sprints on other days.