I had the problem of running out of places to stamp in my passport. I still have nearly 4 years on it. I had already been yelled at by US Imm. for not having a blank space. As I travel intl. so much I did not want to give up my Passport even with expediated service. So, on my cruise from CPH I went to the US Embassy in Tallinn, Estonia and within 15 minutes had the pages added. No fuss, no muss, no charge. Don't know if they can do renewals but if they can and your current passport is still valid but will expire shortly it may be worth a shot.