The Lilywhites put a difficult week behind them with a ruthless demolition of League One high-flyers Colchester, with Jon Parkin scoring a hat-trick and Chris Sedgwick, Chris Brown, a Ben Williams own goal and a Darren Carter strike completing the rout.
Kelly said: "It has been a difficult week, but I am delighted for the players and the supporters. It has ended on a positive note and we're in the hat for the next round.
"We said to them 'affect what you can affect' and no-one can ask any more. They have been very professional the last few days and I think you saw a professional performance and it is the players who get 100% credit for it and no-one else."
Kelly also revealed that there have been no developments with regards to a permanent successor to Irvine.
He added: "We'll report for training on Monday and go from there. It will be business as usual.
"The chairman has been very straight and open and asked me to take training and pick the team today and unless I hear otherwise, I'll report for training on Monday."
Colchester boss Adrian Boothroyd admitted his side were not at the races.
He said: "Everything that could go wrong did go wrong. They got the deflections, a penalty that probably wasn't, but we have to take it on the chin. We can't make excuses.
"It was a very, very, very poor performance and the only thing that was consistent was our fans were clapping and singing all the way through.
"I won't be brushing this under the carpet and writing it off as a freak result, but at the moment we'll get out of Preston as quick as we can. I've learnt a few things today, but I'll mull over them in some quiet time."