The Baggies host the EFL newcomers in the second round of the Carabao Cup on Wednesday as overwhelming favourites.
Albion lost 3-0 at home to Leicester on Sunday as they returned to the Premier League after a two-year absence.
They face Everton and Chelsea in the top flight this month and Harper knows the importance of their cup clash.
"You can't take any team for granted," said the midfielder.
"We have to pay them great respect and they've had a fantastic season last year and you see a lot of disappointments in the cups.
"We have to match their hunger and the intensity that they're going to bring to us and then show our quality.
"It could be a first competitive start in a new season for me so it's a chance to propel myself into the manager's thoughts and a lot of the other players will be out to prove a point.
"During the first game of the season we all got a taste of what the Premier League's like.
"We matched their intensity in the first half and with the mentality of the group, it's just a little setback because we didn't come here to be passengers - we came here to do everything to win matches."
Harper was a second-half substitute against the Foxes as Albion conceded three second-half goals, including two Jamie Vardy penalties, to slip to defeat.
The 20-year-old made 13 appearances in all competitions last term as the Baggies finished second in the Sky Bet Championship.
He told the club's official website: "The manager (Slaven Bilic) has seen a lot of change in me in terms of mentality, work-rate and consistency in performances and he said that I was going to get opportunities, so the manager has stuck to his word.
"I feel like Wednesday's game is very important. First things first, I hope we win the game and I hope we play well because when you win games it breeds confidence and creates a positive atmosphere around the group."