This is pretty cool news!
Airbus says they will offer retrofitted sharklet wing tip devices for older A319 & A320 series jets starting in 2015. They will perform the same retrofit modification for the A321 series jets at a later date.
Currently, sharklets have only been available on newly manufactured Airbus jets. The benefits include about a 4% reduction in fuel consumption and about an extra 100 nautical miles in range.
According to Airbus, sharklet installation can be completed in approximately 13 days.