The Denmark international is set to leave Spurs when his current contract expires at the end of the season.
“I don't see him signing a new contract now," he told The Sun. "I think he will let it run out and take that option of being a free agent next summer.
"So if he doesn't want to stay and has made up his mind to go, I'd be looking to play someone else now.
“If he doesn't want to be part of the team, it's very difficult — you want people who want to play for the club — and it's time to say right, OK."
Redknapp added: “He's not in form and wants to leave at the end of the year — he's stated quite plainly he is keen to go, even though Tottenham must have offered him a new contract."