Lundstram has rejected a new contract offer and his deal will expire in June.
“I'll move on, I'll not think too much about it," he insisted.
“I've got to concentrate on players who want to commit and sign here, like Fleck, (Enda) Stevens, (Oliver) Norwood, (Billy) Sharp, (Chris) Basham, (John) Egan and the new players have.
“I've got to make that (selection) decision, with a short-, medium- and long-term view. Should I side behind the players who have committed to us or a player who doesn't want to be at the football club?
“I believe if John does play, he will do his best. I wouldn't pick him if I didn't think he was in the right frame of mind but I've got to think quite hard."