Duke endured a day to forget at Wembley yesterday as he was sent off during a comfortable 5-0 win for Swansea City.
The 35-year-old admitted that his Wembley debut was very disappointing but wants to put things right by gaining promotion to League One via the playoffs.
He told Sky Sports News: "Today is a massive disappointment. But when we come to reflect on this in a couple of days or at the end of the season, or even in a couple of years' time we'll appreciate what a fantastic achievement it was.
"Hopefully the fans have had a great day and no matter about the result that they've enjoyed it. Fingers crossed we'll be coming back in May to give them another great day.
"If we have a good run between now and the end of the season there's no reason why we can't get back in the playoffs."
The Bantams are currently eight points from a playoff place in League Two but have at least three games in hand on most of their promotion rivals.