While there isn't a set date that has been released yet, SISTAR is scheduled to release a new album. The official said, "Yes, SISTAR is dropping their new album this month but the format of the album and the exact date of their comeback cannot be revealed yet."
SISTAR released their 1st studio album last year, "So Cool," and made waves with their title track of the same name, winning several awards. In addition, SISTAR became the first artist to top the newly created Billboard K-Pop Hot 100 Charts with "So Cool."
Source: 10asiae & koreaboo