Mitchell enjoyed a stellar 2012 season averaging 27 possessions in 24 matches, and Ratten says the club has already earmarked new ways to challenge the former skipper.
Ratten told the Hawthorn's website Mitchell could improve his work away from stoppages, where he is considered one of the competition's best players.
"All players can keep learning and it will be for me to challenge Sam in the way he plays and where's the next bit of growth for Sam Mitchell," Ratten told hawthornfc.com.au.
"Is it going to play away from the stoppages, some of those things I would like to challenge him on about keeping his longevity in the game.
"For a player of his skill and who hasn't had many injuries … we want him to start to do other things in the game."
Mitchell, 30, ranked fourth in the AFL in clearances in 2012 and Ratten said he ranked amongst the best stoppage players the game had seen.
"What he does around the ball is as good as I've seen. We'll just try and add something different to his game."
A look at his 2012 figures illustrates Mitchell's dominance and importance at the Hawks.
He ranked first in goal assists in the AFL, second in effective disposals, sixth in tackles, seventh in contested possessions and eighth in total possessions.
He also managed to collect 30 or more possessions in eight matches.
In October, Mitchell was crowned Hawthorn's Peter Crimmins Medallist for the fourth time.
Ratten joined the Hawks in October after five-and-a-half seasons coaching Carlton.
A star midfielder in a 255-game career with the Blues, Ratten will work with Hawthorn's onballers in his new role.
