Hello mate. Audi will tell you they are sealed for life and the fluid will never need changing......If this were true they wouldn't have drain and refill plugs! lol! I changed mine a few months back (@ 125,000), because IMO its good practice. Just dont make the mistake of buying the fluid from Audi as they charge the earth. Get it from GSF or ECP. I can't remember the grade/specification, its in my SH, but I am sure someone will let you know.
Ollie
P.S. - Be carefull when undoing the plugs, Aragorn is having a knightmare with his at the mo, and make sure you undo the refill plug first!!