The scheme was suspended a month ago after only seven weeks due to the rapid global spread of the Omicron variant and uncertainty about vaccine effectiveness against it.
The policy requires visitors to test on arrival and again five days later, while agreeing to have their whereabouts tracked, spokesperson Taweesin Wisanuyothin told a briefing.
Authorities also extended the hours restaurants are allowed to serve alcohol to 11 p.m. from 9 p.m. Bars and nightclubs will remain closed, however.
The moves are aimed at reviving a tourism sector that has been decimated by the pandemic, with numbers limited by weak global travel demand and Thailand's rigorous quarantine requirements.
Visitors last year to Thailand, one of Asia's most popular travel destinations, were about 0.5% of the pre-pandemic figure, which hit a record of nearly 40 million in 2019.
The taskforce also agreed to expand another similar quarantine waiver programme, the "Sandbox" to include popular eastern beach destinations Pattaya and Koh Chang.
The scheme, where vaccinated tourists must agree to stay in one location for a week, is currently operating in Phuket and Koh Samui.
Thailand has reported 2.3 million infections and nearly 22,000 coronavirus-related fatalities overall. About two-thirds of residents have been vaccinated and 15% have received a booster.