The 26-year-old, who was brought to the club by Andy Scott last summer, has been beset by injuries and only made seven appearances.
"The kid has suffered with a bad injury but he is only four or five weeks away from recovery and as I said to him the summer has come at a good time for him because it gives him time to work hard and get right," said Evans.
Foster follows Richard Naylor, Ollie Banks and Marcus Marshall out of the club, with the rest of the squad set to learn their fate on Monday afternoon.
Meanwhile, veteran goalkeeper Andy Warrington has agreed a one-year deal to stay at the club while popular player-coach Paul Warne has penned a three-year coaching contract.
"Warney was desperate to stay because he has Rotherham United running through him and it was important we gave the lad the opportunity," Evans added.