Lennon is struggling with a long-term groin injury that has kept him out of action since December.
“He is seeing a specialist tomorrow,” said Redknapp on Wednesday. “We just hope we get some good news from Aaron.
“He is going to see somebody abroad and hopefully we can get somebody who can get to the bottom of the problem for him because he is desperate to play.
“It’s shame for him and it’s a shame for us. We all miss him, he is a fantastic player.”