Sense, the Big Issue Foundation, the National Autistic Society, St John Ambulance and Whizz-Kidz shared £122,940 from last week's draw, when ticket sales fell by 13.5 per cent.
Chariot's share price has fallen from a high of 213p on 25 April to 38p last Friday.
The company would not say what changes it would make, but Craig Freeman, its managing director, blamed an unfocused advertising campaign for the poor sales.
"The problem is that people don't understand us," he said. "That's because our advertising carried different messages in different media, which meant people had to pay attention to every part of the story.
"They understand that we benefit charities, but they are not sure about who we are, why we do it or how."
He added that broadcast advertising restrictions, which prevented Chariot from making direct comparisons between its monday game and the National Lottery, had not helped.