Each approved extension request will allow you an additional 6 months to submit your Statement of Use form. You can submit extension requests for up to 36 months (up to 6 requests) after the U.S. Patent and Trademark Office (USPTO) issues a Notice of Allowance (a temporary, conditional approval of the trademark application). To view the date of your Notice of Allowance, visit
http://portal.uspto.gov/external/portal/tow and enter your trademark's USPTO Serial Number.
LegalZoom can help you file additional extension requests.