The highly-rated midfielder has impressed during his time with the R's, making 14 appearances and helping Redknapp's side make a push for promotion back to the Premier League.
However, with injuries to the likes of Sandro, Paulinho and Gylfi Sigurdsson, it is reported that Spurs boss Tim Sherwood is considering recalling the England U21 midfielder to act as cover.
However, Sherwood is yet to make a decision, and Redknapp is keen to know as he will have to look for a replacement for Carroll.
"I'm not sure what's happening," Redknapp told the Fulham Chronicle.
"It's up to Tim Sherwood what he wants to do. He likes him an awful lot and has been excellent for us.
"I haven't spoken to Tim for a week or so, but if he wants to take him back I need to know because we need time to try and find somebody else.
"I wouldn't want to leave it until the last minute [of the window]. It's a difficult time of year to find players."