He said: "We don't have cover for Jamie McAllister on the left side. When we let Paul Hartley go we lost probably our most creative midfielder."
"That's the two areas we'd like to strengthen in January."
He added: "We've got six players in our development squad and 12 out of contract in the summer.
"We need to move some of those players on in January, instead of losing them for nothing in the summer.
"There are some out of contract players we want to keep and we'll be speaking to them."
He's been terrific since he's come here and Tottenham are delighted with his development
Keith Millen on Steven Caulker
Millen took over from Steve Coppell in August following the former Reading manager's shock decision to quit.
During his short stint at the club Coppell signed Nicky Hunt, Damion Stewart, and Tom Williams, who have rarely featured for Millen this season.
He has brought in strikers Jon Stead and Brett Pitman along with Spurs pair Danny Rose and Steven Caulker on loan.
And the City boss confirmed Caulker would remain with the club for the season and review the situation in the summer.
"He's been terrific since he's come here and Tottenham are delighted with his development," he said.
"We have regular conversations with Tottenham and they were pleased with his call-up to the England Under-21 set-up.
"I'd like to think that had something to do with how well he's playing for us and Steve Wigley's involvement.
"We've got him on loan until the end of the season and we're led to believe he's highly thought of in Tottenham's long-term plans.
"Maybe if he feels he can't get regular games at White Hart Lane then he might have to move on but I don't know if that will be the case."
Source: BBC Sport
Source: BBC Sport