Palace face Watford tomorrow night in the Premier League promotion playoff final.
Redknapp told The Sun: "I know the people who are behind Ian Holloway at Crystal Palace.
"Steve Parish has got the place running well now.
"Palace have had their ups and downs behind the scenes for years so it's good to see the club on an even keel at last.
"Ollie knows he will have to get busy in the transfer market if he brings them up.
"You are looking at four or five players of the quality needed to hold their own in the top flight. Ian of course is going to lose his best player in Wilf Zaha, who is joining Manchester United in the summer."