Don't Fight It
What I'm trying to say is two things: Firstly, if you haven't been running long and think your race-times have plateaued, keep trying; and secondly, don't fight it. Do the training you think will produce the desired result and the times will come. Eventually. Consistency and patience count for a lot.
By tomorrow I'll have run 70 kilometres for the week (my biggest week since late July). I enjoyed my first interval session on the grass at Stromlo last Sunday — 3 x 1k in 4:34, and on Tuesday ran some continuous laps on the lush grass of the Calwell Track. I can tell that I'm not yet fit enough to race well (which I'd define as 22 minutes for 5k). I guess I'd run 24 minutes. I think I'll "race" the Cross Country Club 5k events on Tuesday afternoons (as tempo efforts) to ease my way back into the racing scene.