Berks previously enjoyed a spell at the Castle in 2020/21, having first joined the club from Chasetown.
He also lists Port Vale and Stafford Rangers amongst his former clubs.
Manager Paul Moore said: "Joe's had a couple of games behind him now and we're really positive about what he can bring to the group.
"He's settling in well and will play a key role in what I'm sure is going to be a very exciting season for him and for the club as a whole."
Berks becomes the second player to commit to the club in recent days, with fellow midfielder Joe Thompson signing on the dotted line last weekend.
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