I stand corrected! From the AS Mileage Plan booklet.
Changes to Redeemed Awards
For a $50.00 standard service fee, the following changes may be made to unexpired Mileag Plan awards: traveler name change (for unused award and tickets only), award extension (for unexpired award certificates only), exchange for an alternate award or redeposit of mileage for returned awards. Please allow at least three weeks for processing.
Award certificates may be reassigned to the member named on the certificate without a service fee if the designated traveler is unable to travel.
A change in routing on a ticketed award may be made prior to departure for a non-refundable $40 service charge to a major credit card. Call Mileage Plan for detail on these award change options.