The striker's current deal expires in the summer and reports have suggested that Australian side Gold Coast Galaxy are keen to snap him up.
Kanu needs to make 25 appearances this season to earn a contract extension and he has so far played 20 times.
The Nigerian has struggled with a knee problem at times this term - but Redknapp is hopeful he will be able to feature in at least five more games.
"If he takes part in 25 games he'll get another year," Redknapp told The News.
"I love having him around and all the other lads love him, too.
"His knee is a bit of problem - it's a bit iffy at times - but he's unique. Some of those things he can do are fantastic to watch."
The Pompey boss is looking ahead to the FA Cup quarter-final against Manchester United a week later and is desperate to have Kanu available.