Rovers went down 2-0 in the fixture that was being replayed after getting abandoned back in August because of torrential rain in South London.
That day Rovers were leading 3-1 when the game was called off at half time, but Dickov didn't want that fact to be used as an excuse.
"We had six players missing from the abandoned game but take nothing away from Charlton, they looked half a yard sharper than us," BBC Sport quotes Dickov as saying.
"It grated at the time maybe but I can't let it go now. I'm not going to make excuses, we should have done better than we did.
"We didn't match their desire and Charlton wanted it more than us."
Donny have dropped a place to 20th in the table but remain five points clear of the relegation zone.