Substitute Keanu Marsh-Brown struck five minutes from time on his debut to secure a 1-0 win for Barnet at Kingsmeadow, leaving the two sides level on 48 points and three clear of York in 23rd.
After seeing the Dons' unbeaten home record in 2013 come to an end, Ardley urged his team not to waste their good work.
He said: "We didn't win but we can't moan about it. Perhaps if we got our set pieces right and we had a bit more quality we could've been one up at that point but we didn't.
"I'd be surprised if 51 points isn't enough but it's not the case of one more win and shut up shop, it's the case of one more win and then go for the second.
"It just means the pressure is still there. We've been mentally strong, we've dealt with the pressure for the past three months and we can't let the good work go to waste.
"We'll rally the troops, it's my job to pick them up and take them forward.
"This is the league this year, it's one of those leagues. League Two will be a battle till the end.
"I didn't think they were a threat. That's my opinion and I might be wrong. I thought there was only going to be one team to get the win in the second half. It's really disappointing when a slip-up costs you."