This may seem counter-productive but it's worked for me: the best way to improve my speed has always been to stop worrying about it and focus on the distance instead. Once I get to a certain point (right now I'm just under 3.5 miles, it's that time for me...) I lose my watch, and work on running a little further every day. The watch is great when I'm doing interval work, but once I finally get into long distances, it can really **** me up. Sort of the same way that getting on the scale every day can. I focus too much on what kind of time I'm running, get discouraged if I feel like I'm going slower than I want, or push too hard early and gas out late, even just stare at the watch for a half hour. Which is like torture. So I take it out of the equation. It lets me just focus on the running itself, and I can lose myself in it. Every so often I'll time the run just so I have a general idea, but it seems to help me to focus on where I'm running, and not how long I'm running.
Now, I run outdoors. Can't do that so much on a treadmill, so people's mileage will vary (I can't run on a treadmill at all; I'd rather be waterboarded). But this approach got me from @13 down to @9 last year.