Lee took the first game by upping his attacking game in the final stretch as Liew battled to close the gap at 16-17.
Several cross-court smashes could only be watched by the 34-year-old as Lee finished off with a flurry to ease into the lead.
But Liew stormed back to level matters with a 21-13 victory in the second game to head into yet another three-game contest for Lee in this tournament.
Lee was not to denied of a second consecutive final, taking the deciding game with a comprehensive 21-14 win.
He would contend for the title against Li Shifeng, who overcame Kodai Naraoka in a marathon battle in the other semis.
Lee is the country's only representative in the final after Pearly Tan-M. Thinaah and Aaron Chia-Soh Wooi Yik both lost their matches.
Tan-Thinaah went down 17-21, 17-21 to Japanese pair Nami Matsuyama-Chiharu Shida, while Chia-Soh lost 19-21, 14-21 against Fajar Alfian-Rian Ardianto.