Barnett gets his chance due to injury to striker Jamie Slabber. Lee Barnard will revert to his favoured striking role and Barnett will slot into midfield.
16-year-old striker Michael Malcolm is also added to squad and will feature on the bench.
"We need to up our game a little bit," said Pat on Tuesday. "I've changed it slightly, I've brought a young lad in called Lee Barnett and it's going to be a big game for him at such a late stage of the competition.
"I've also brought a young lad in called Michael Malcolm, who is going to be on the bench. We're just trying to spice it up a bit and see if we can get something out of it.
Pat hopes that, should his team overcome a 2-1 first leg deficit and reach final, influential striker Slabber - scorer at both Bolton and Leeds in previous rounds - will have recovered from ankle ligament damage.
"Jamie won't be fit. He took a knock about five or six weeks ago and has never recovered from it. He turned out in the Blackburn game and wasn't himself and I think it's just a culmination of the injury.
"Hopefully, touch wood, we'll get through to the final and then we'll have a fit Jamie Slabber.
"Lee (Barnard) will revert to striker, which is his best position, and Lee Barnett will come into midfield with (Dean) Marney, (Nicky) Wettner and (Mark) Hughes.
The Youth Cup semi-final, second leg takes place at White Hart Lane on Wednesday evening, kick-off 7pm. Admission is £3 adults, £1 concessions.
Midfielder Lee Barnett, a 17-year-old first year trainee, has the chance to make his mark on the big stage as Pat Holland introduces him to his FA Youth Cup side for the semi-final return against Everton at the Lane.