You can easily renew your passport by following the instructions below. However, it is important that you apply early. How early?
Many foreign countries require your passport to have at least six month”s validity remaining before they will issue a visa. Add to this the time required to process your passport and you get a total of eight or nine months.
You should apply for a passport renewal if:
Already have a passport that is not damaged; and

Received it within the past 15 years; and
Were at least age 16 when it was issued; and
Still have the same name as in passport (or you can legally document your name change).
To apply for a passport renewal, you need to send in the following items by mail.
1. Completed Application For Passport By Mail , form DS-82.
The form can be downloaded at the U.S. Department of State web site or the sites of many travel agencies and travel document expediters.
When filling out the form, check everything twice. Be sure to sign the application.
2. Your most recent passport.
Your previous passport will be returned to you along with your new one.
3. Two identical passport photos.
The two photos must be 2 x 2 inches, identical, taken within the last 6 months. The photos must show a full face, front view with a plain white or off-white background. You should dress in normal street attire. Uniforms, except for religious retire that is worn daily, hats, headgear and dark glasses are not acceptable. Prescription glasses with clear lenses are.
4. Applicable fee.
The fee to renew your passport is $67. Payments should be made out to U.S. Department of State.
If your name has changed, include a certified copy of the legal document specifying your name change (e.g. marriage certificate, divorce decreee, adoption cdreee, or court order).
Gather all the appropriate documents and place them in a padded envelope. Send it to the address below:
National Passport Center
P.O. Box 371971
Pittsburgh, PA 15250-7971
If everything goes well, your application should be processed and your renewed passport sent to you within about 6 weeks.