The North London side can go level on points with Manchester United in second place in the league table if they defeat Everton this evening.
"We have improved this year, we are stronger," said Redknapp. "It is just that belief. We have to believe we can do it and have that belief that we can keep challenging.
"I am not going to say 'We are going to win the league' as it is going to be very difficult. Just look at Man United's squad and City's squad, they have fantastic players and can make changes everywhere. Their forward players are incredible.
"[Sir Alex Ferguson] will look at it and say 'They are going well, they are playing well'. He is not disrespectful to write us off completely. It will be difficult for us to finish above them or Man City, but you just never know do you?"
Spurs face Everton tonight due to the original fixture being postponed following the London riots in August.