The Croatian international, 29, is currently at the Championship club on a season-long loan deal from Dynamo Kiev.
"You would love to have him here [permanently], but the end of the season is a long way off, so let's see what happens this year at QPR," Redknapp told the Fulham Chronicle.
"I don't know exactly what the situation is. They paid a lot of money for him. We'll have to see what happens."
Kranjcar has previously played under Redknapp at Portsmouth and Tottenham Hotspur.