"Ronnie's been on a three-year contract with a one-year option which I've been told has been invoked by the club," Sillett told Sky Sports News.
"The deal has been proposed on if the club should stay up and he met certain criteria, which he has done, which amounts to playing a certain number of games this season and he has met those targets.
"Really the final offer reaches a level which would be a lot less than some are on in The Championship.
"We are hoping to extend that contract and I can't see why we can't iron that out."