The 0-0 draw with Barnsley at the weekend was their fifth league match without a win, while they have not scored in four of their last five games.
"The games are slipping away and we wanted something slightly better than this," Holloway told reporters at a press conference.
"Confidence is a very simple thing but it's a very hard thing to get it. If I could bottle it and sell it, I'd be a multi-millionaire."
Palace currently sit fourth in the Championship table.