Booked one plane ticket, now airfare goes down....help?

I bought a plane ticket for travel in September, and the fare was about $210. A week later the fare is only $130, including all taxes and fees. The first ticket was non-refundable, bought from Cheaptickets.com. The cheaper ticket came from US Airway's website. Is there anything that I can do to get rid of the 1st ticket and buy the 2nd?