Gary Johnson felt his side were unfortunate not to guarantee a place in the second round after they were held a 1-1 draw by Stockport.
Robbie Williams fired the Hatters into a 20th-minute lead, before Aaron Mclean levelled things up eight minutes later, meaning the two sides will have to do it all over again at London Road.
"Really, the game should have been with us," he said. "Their goalkeeper made four or five one-on-one saves and he was rightly the man of the match.
"We really should have got two or three. We've been scoring regularly but in this game we didn't, but we live to fight another day.
"They've got a lot of young lads and they've hung on well. They did stay in it, they forced a couple of saves early on but we're still in it.
"I brought Grant McCann in to a four-man midfield and I wanted us to get on the ball and we did that, we just didn't get the end result."