The first phase covered about 43 million people and ran from June to September, with participants receiving 1,000 baht (US$30.04) per month.
The government subsidized 60% of eligible purchases, capped at 200 baht per person per day.
The extension, subject to cabinet approval, is aimed at helping ease living costs.
"This is not a populist policy. It is both an economic stimulus policy and a measure to ease people's expenses across the country at a time of high living costs," Anutin said.
The extension will last two months, a government spokesperson said.