When the profit box pops up after closing business in the game, do not click OK. Click on the smiley icon above, and the system will ask you whether to upgrade. Just click "Yes".

The first level: 5,000 yuan, 5 dishes, takes one day

The second level: 10,000 yuan, 10 dishes, takes two days

Level 3: 50,000 coins, 14 dishes, takes three days

Level 4: 100,000 coins, 16 dishes, takes four days

Level 5 : Two hundred thousand Wen, 20 dishes, five days spent

If the upgrade conditions are met, a smiley face will appear after closing, and you can choose whether to upgrade immediately.