The ad, which will launch on Channel 4 during Friday's Big Brother final, is understood to include footage from both "gorilla" and Fallon's follow-up ad "trucks". It will not include new footage, but industry insiders say it will feature a new soundtrack.
In the original ads, the gorilla was seen drumming to the Phil Collins track "In the Air Tonight", while "trucks" featured animated airport transport vehicles racing down a runway to the Queen song "Don't Stop Me Now".
The ad's launch on Friday coincides with the one-year anniversary of the original "gorilla" commercial, which first aired during last year's Big Brother final.
The campaign has gone on to achieve worldwide acclaim, and scooped the Film Grand Prix at Cannes this year.
Fallon and Cadbury declined to comment.