Im not sure if this would help you; but i have found if I train with people who are faster than me I train better. If you find someone who is running a faster pace than you try to see what their workout plan is than maybe you can run with them. Eventually this will make you faster. I ran cross country in high school; I know that worked for me. Though I am new to all this half marathon stuff.

I concur with Rogue, Hal Higdon's stuff is very practical and stood the test of time.