The 26-year-old midfielder got an extended run on the pitch, with the game going into extra time.
Harrop’s last appearance for PNE was on Boxing Day 2020 as an 82nd-minute sub in a 1-0 win over Derby County at Pride Park.
North End manager Lowe said: “I had a meeting with Josh last week, I spoke to him and his agent.
“He just wanted to know where he was at, with him having been out on loan and then injured for a bit.
“Since I have come through the door, he has been fighting for it, trying to get fit and trying to showcase his talents.
“That is what he has been doing on a daily basis in training.
“The aim against Cardiff was to get him minutes and he got those.
“Josh obviously needs to get a lot fitter because of the way we play. That is not his fault, he just hasn’t played a lot of football recently.
“He will get up to speed with more training and fitness work.”
Harrop didn’t particularly impact Sunday’s game, in fact none of the five subs used really made a mark.
But the former Manchester United man would have seen it as a big step forward just to be on the pitch again.
Said Lowe: “It was nice for me to see him on the pitch, not just in training.
“I thought he was good in spells although it was hard for those coming on.
“At one point he ran across to the other side of the pitch because he wanted to get on the ball and impress. He will impress me more by doing the simple things.
“It was good to have Josh back in the fold and he can get more work done this week.”
Harrop spent the second half of last season on loan at Ipswich Town but made only three starts – he came off the bench in 12 games.
On his return to Deepdale in the summer, he featured in some of the pre-season friendlies.
Early on in the season Harrop was an unused sub a couple of times.
He wasn’t included in the 25-man squad submitted to the EFL for Championship games at the start of September.
In the meantime, Harrop got injured and didn’t feature in any reserve games.
Meanwhile, PNE’s visit to Swansea on Saturday, January 22, will have a 12.30pm kick-off. The early start is allow the game to be live streamed as it is being played behind closed doors.