Ankle injuries forced both players off during the 2-2 home draw with Port Vale.
Cooper has a chance of being fit to face the Bees but the fear around the Proact Stadium is that Richards, who scored both the Spireites' goals against his former club on Monday, may miss more than just the game against Edgar Davids' side.
Skipper Sam Hird is likely to replace Cooper while veteran striker Jack Lester could come in for Richards. Scott Boden is also an option up front for Blues boss Paul Cook after he was recalled from his loan spell at Alfreton on Thursday.
Chesterfield kept their slim play-off hopes alive with four points against Burton and Vale over the Easter period and another win at Underhill is a must if the Spireites are to have any chance of gatecrashing the top seven.
Assistant manager Tommy Wright said: "We have to go to Barnet and play exactly how we have been playing. We can't let ourselves down.
"It's been a frustrating season, but we've still got a slight chance and while you've got that chance you've got to believe."