The midfielder's current deal at Villa Park is due to expire during the summer, which would make him available for a free transfer.
However, Lambert has hinted that unless the 21-year-old can force his way into the starting lineup, his days as a Villa player could be numbered.
"He's trained the last few weeks now and he was on the bench at Liverpool. He's doing all right. It's hard for him to get in the side at the minute and he knows that himself, but he needs games that's for sure," Lambert told the Birmingham Mail.
"He's out of contract in the summer and he's in the same boat as a few of the others. There's too many games to play to worry about that yet. It will be resolved in due course."
Gardner has risen through the ranks at Villa following his arrival as a trainee in 2005.