Redknapp’s side were competing with Manchester City and Manchester United until a slump in form which saw the Londoners manage just one win in nine attempts ended their title bid.
Luka Modrić and Gareth Bale have been linked with summer moves away from White Hart Lane, but a defiant Redknapp wants further investment in the squad to help close the gap on the two Manchester clubs.
“We’re a good side. If we’re bold in the summer, we can build a team again that can be right there again next year,” Redknapp told BBC Radio Five Live.
“The league is changing and a top-four position is very difficult to achieve.”
Tottenham are a point behind third-placed Arsenal after their 1-1 draw with Aston Villa on Sunday and with one game left – against Fulham at White Hart Lane – the 64-year-old manager admits he is desperate to achieve a top-four finish.
“I’ll be glad when next week is over. It’s been a long old season. I just want to get in the Champions League and have a break and get away for a few days,” he added.
“It has been a hard year for me personally. What I went through with the court case was the most difficult thing I’ve ever faced in my life.
“It definitely takes a strain on you. I do tend to get on with things but there’s no doubt it has an effect.”
MORE: Man United latest news
MORE: Arsenal latest news
MORE: Chelsea latest news
MORE: Liverpool latest news