Antonyms for the phrase "lost one's interest" include various expressions that depict a renewed or heightened sense of attention, involvement, and enthusiasm. Some of these antonyms are: gained interest, sparked fascination, aroused curiosity, kindled passion, regained one's focus, revived engagement, rejuvenated attraction, invigorated attention, aroused stimulation, revived captivation, and rekindled ardor. Using these antonyms can add a positive and proactive tone to your language, and help communicate a rekindling of interest or motivation. Instead of focusing on diminished interest, you can highlight the revival of positive feelings, which can lead to increased engagement and productivity.