The Blues are without a win in three games after slipping to a 1-0 defeat against Leamington on Saturday.
And Johnson knows his side has to be more clinical if they are to achieve their aims this season.
"We paid for our missed chances today," he told the club's Twitter service. "You come to places like this and it's not nice, it's hard enough to get a result as it is.
"But when you're gifted the opportunities we were today, we've got to take them if you want to be top of the league because they come back to bite you.
"Defensively there's not really a concern because we're not leaking goals here, there and everywhere. But we've got to be better and take responsibility which I'm quite sure certain players will.
"We've had a great run so it's important we pick ourselves up, dust ourselves down and look forward to training on Tuesday.
"We're just not getting the easy stuff right at the minute but I can't criticise the work ethic because in terms of work rate, we'll match anybody."