The group, which operates brands Revolución de Cuba and Revolution, outlined its results for the 26 weeks ended 29 December 2018.
Chief executive officer Rob Pitcher said priorities needed re-evaluating with Revolution, though pointed to good performance at Revolución de Cuba.
A new site opening programme at Revolution has been halted as attention shifts to refurbishing sites.
Like-for-like sales across brands declined 4%, with Revolution sales declining because of under-investment, made worse by management instability and a warm summer.
Christmas trading saw a positive boost, with a sales increase of 2.6%, a sixth consecutive year of growth in the four-week festive period.
"While Revolución de Cuba has performed well and delivered growth in the reporting period, it is clear that the lack of investment into the Revolution proposition is impacting performance," said Pitcher.
"Revolution has been reviewed, the issues identified, and work streams are being implemented to restore it to growth."
Problem areas identified with the Revolution brand include speed of service, customers looking for experience-based trips and a lack of menu innovation.
Customer research also suggested to the group that the estate “may benefit from a segmented offering”.
Pitcher added: “Our confidence in achieving this is underpinned by the good performance of the new Revolution venues, while the recently refurbished sites are also seeing uplifts.”
“We have, therefore, decided to prioritise the refurbishment programme over new openings.”
New openings and refurbs
Three Revolutions were refurbished last month and a further three revamps are planned.
The group walked away from discussions to acquire Deltic, the operator of 55 bars and clubs, last autumn.
It said the transaction “would not be in the best interests of the company’s shareholders,” in a statement.
A challenging trading period was recorded for the first two months of the year (to 23 February 2019), attributed to refurbishment closures, Valentine’s Day falling on a Thursday instead of Wednesday’s student-focused day, and later half-term holidays.
“We expect trading to improve as we come up against softer comparatives for the rest of the financial year,” Pitcher added.
There are now 60 Revolution and 19 Revolución de Cuba sites across the UK.
Trading has been positive at the five sites opened in the period, which include sites in Glasgow, Southampton, Bristol, Huddersfield and Durham.