The initiative is part of a refurbishment of the Wine Rack estate launched last month.
The group declined to provide figures, but some London stores are already being converted to the blue Wine Rack fascia.
A Thresher spokeswoman said: “The investment in Wine Rack stores is a key component of our customer-focused brand strategy. The main priority is upgrading the Wine Rack brand.”
The initiative is one of the first under chief executive Yvonne Rankin, who joined in September, after Roger Whiteside left. In October, it hired Patrick Copeland as chairman.
After joining, Rankin and her team conducted a 100-day review, the results of which are scheduled to be unveiled next month, in an effort to turn around Thresher’s flagging profitability and sales.
Next month, the retailer is expected to reveal details of plans for its 2,000 stores – which include The Local and Scottish chain Haddows – as well as franchising, wholesale and the addition of a small convenience food offer in Thresher stores.
Last July, a consortium led by Edmund Truell agreed to sell 75 per cent of Threshers and its entire stake in BrightHouse to Vision Capital for more than£250 million.