Nelsen’s current contract is set to expire in the summer. The New Zealander joined Spurs from Blackburn on a free transfer in January.
Nelsen scored his first goal for Spurs during Tuesday night’s FA Cup quarter-final against Bolton.
“I thought he was fantastic tonight,” Redknapp told Skysports.
“I just think he is a great professional and a real good player. I couldn’t believe I got him on a free.
“I felt it was an amazing player to bring to the club – he is a player I have chased for years. I have always thought he was top class, a great pro, a great trainer, a fantastic person.
“He has got a six-month contract. At the end of the season you have got to keep him here next year because he’s worth his weight in gold just to have around for other people to look at the way he works, the way he trains, the way he behaves, his attitude.
“That’s what football clubs are built upon, people like him, Scott Parker, Brad Friedel. You bring them in and it changes everything. That has been the difference this year.”
