The soft drinks company has hired LBi to handle the redesign of the online hub for Coca-Cola, Diet Coke and Coke Zero, following a pitch against Dare.
The digital agency will be responsible for all content on the Coke Zone site, which is intended to boost consumption of Coca-Cola products among young adults and teenagers.
The push will also involve stepping up Coke Zone's mobile and social-media activity.
Website visitors must enter a 12-digit code, found on Coke, Diet Coke and Coke Zero packaging, to access deals.
They can then collect points, which can be redeemed for offers such as two-for-one Blockbuster film rentals, or used to enter competitions to win bigger prizes, such as a Samsung laptop. The site also offers Coca-Cola-branded items.
Prizes and content are spread across the entertainment, games, fashion, sport and music categories.
Coke Zone, created by Carlson Marketing, was launched in 2008. Its roll-out was backed by a £5m integrated campaign, including print, TV, digital and in-store activity, created by VCCP.
In January 2009 Coca-Cola refreshed the scheme to make it easier to navigate and to offer consumers a richer media experience.
Following the revamp, the company ran a giveaway promotion on cans and bottles of Diet Coke. Consumers who entered the on-pack codes via SMS or on Coke Zone throughout February could win a daily prize of £10,000.
The push, aimed at Diet Coke's core female market, was the brand's biggest for 15 years.
According to comScore data, in January 2008, the month Coke Zone was launched, it had 59,000 unique visitors. Traffic peaked in November 2009 when it attracted one million unique users. However numbers more than halved the following month and have continued to slip. In November 2010 it drew 232,000 visitors.
Coca-Cola and LBi declined to comment.