Some additional info would probably help potential responders?
(1) Is the wear on both boots, or just one?
(2) Is the wear on just one side of the ankle, or both sides?
(3) What is the make/model of boot?
(4) What is the liner made of (e.g., leather or microfiber)?
(5) Are you sure the rest of the boot is in good enough condition to be worth salvaging? I've only had this happen to me once. That was an old pair of Riedell Royals with calfskin linings. By the time the lining wore through, the rest of the boot was fairly shot. I don't have enough experience with the service life of other liner materials (such as microfiber).