Ashcroft was part of the Kilmarnock team who overturned a one-goal first-leg deficit to beat Falkirk 4-0 and retain their Scottish Premiership status in 2016.
But Ashcroft ended up dropping down a division anyway after being released and joining Dunfermline. The defender has now spent five seasons in the Championship, four of them at East End Park.
The 27-year-old is now looking to ensure his career comes full circle after helping Dundee beat Killie 2-1 in the first leg of the play-off final.
Ahead of his return to Rugby Park, the centre-back said: "It's a long time ago that I left. I loved my time at the club but it never worked out. I was glad to finish on a high and keep the club in the division.
"I hadn't played many games that season but I got in for the play-offs and managed to do well and keep the club up. I look back and it was a great experience to go through.
"I am looking to do the opposite now and get Dundee back where they belong.
"I'm a Dundee player now and I want to get Dundee back in the Premiership, that's I was brought in here for. Hopefully I can be a part of that and do my job on Monday.
"It would be amazing in my first year at the club. I have obviously been in the Championship longer than I wanted to be but that's down to myself as well."
Ashcroft feels this play-off campaign has been easier to handle than battling to stay up.
"I have been in Kilmarnock's position before with Killie and it feels as if the weight of the world is on your shoulders," he said.
"I know it's a game of football but it means so much to so many people.
"It depends on the person as well. I was still youngish and it was tough.
"But I am feeling different this time. It feels much better. It's good pressure, we are looking to achieve something good.
"Hopefully we can get there in the end and I'm sure the feeling after it will be great."
Brandon Haunstrup's late goal at Dens Park gave Killie a lifeline and Ashcroft needs no warning about the danger of a one-goal first-leg lead.
"It was the same when I was there, we were a goal down and Falkirk came to Rugby Park and we managed to put on a performance," he said.
"They will be looing to repeat that, they have experienced players in their team that have been about and know what it takes.
"We know it's going to be a battle and we need to be 100 per cent at it to give ourselves a chance."