The rebrand, which is being rolled out in May, will include fresh packaging and the addition of several flavours, including a kiwi fruit variant.
Britvic intends to reposition the brand to achieve greater standout from competitors.
Design agency JKR has worked with J2O since the brand's launch in 1998. Bartle Bogle Hegarty handles its creative work and Elvis Communications its direct activity.
J2O was developed to be sold in pubs, bars and restaurants. Britvic claims it is now the second-biggest bottled drink sold in pubs after lager brand Budweiser and that seven bottles of it are sold every second.
In 2002 J2O was introduced to supermarkets, backed by a £1.5m campaign promoting it as a healthy and practical alternative to alcohol. The brand leads the adult soft-drink category, but last year sales grew by just 3.1%, more than 2% below the category's overall growth.
Britvic posted a 1.4% rise in like-for-like sales for its UK still drinks in the 12 weeks to 21 December 2008. It said the licensed on-premise soft-drink market had declined 5% in the three months to November 2008 and that, while Christmas had provided a short-term respite, it did not expect sustained recovery in the near future.
Britvic declined to comment on the relaunch.