While Cathay Pacific’s Asia Miles program isn’t one through which I book many awards, one nice perk of the program is that they allow free date changes on award tickets. Per their website, it appears as if this will change as of October 8, 2013:
Airline Award Ticket Re-booking
Applicable only to change of confirmed flight date or flight number for tickets issued on or after 8 October 2013, with the same itinerary, same airline, and same ticket expiry date. Charge per flight sector per passenger.
The fee for such a change will be $25 or 1,000 miles per sector (which can add up if you’re changing multiple sectors).
(Tip of the hat to jackson)