With two-thirds of the season remaining and the club fighting for silverware in three competitions, Redknapp is reluctant to deplete his squad.
"It's difficult because the players want to play. You won't keep them happy [if they're not]. You just hope you can convince them [to stay]," Redknapp said.
"You want to keep them happy and onside. We need them. We're going to need a big squad and unless you can get a replacement, you can't afford to let people go.
"We need that strength in depth, especially if we stay in Europa League."