The 37-year-old has been restored in a Three Lions shirt since the arrival of Fabio Capello and has subsequently fixed his sights on being England's first-choice goalkeeper at the next World Cup.
"He's such a perfectionist and will be around for a long time yet," said Redknapp. "He's a great trainer and it's not a problem for him.
"He works non-stop on the training ground and he studies videos of his performances every afternoon.
"He's absolutely dedicated and he's in such great condition."