@scrappy, hill work is always good (I seem to run farther on hills for some bizarre reason), but you need not go there yet necessarily.
It’s good that you know the time of day and place where you feel you run the best. Try to stick with that as a mental advantage oft times becomes a real physical advantage, too. (Meaning, if you believe you are going to run fast and far, then chances are you actually will).
Treadmills are okay if you’ve got nothing else available, but if you can consistently make your runs outdoors, you should see better results faster.
You might also be trying to run too fast. What kind of pace are you usually at? Can you pull it back just a little bit?
Finally, there are many alternatives, but a popular item that I find immensely helpful is the iPod Nano with the Nike+ kit for tracking your runs. Do you have something to help track your distance and pace? Used in combination with chica’s excellent suggestion, you can find yourself getting excited seeing improvements coming across each time.