Often, a project's execution does not adhere to the original planned schedule. In such instances there is a need to reschedule projects to re-evaluate timelines, costs etc.
When you wish to reschedule a project, or projects:
in the Summary view, select all the projects you wish to reschedule
use the menu option Schedule → Reschedule selected project(s) from today
if there are any partially completed tasks among the selected projects, the dialog shown below will appear
selecting Auto-split partially complete projects will cause partially completed projects to be split into two parts, one of which represents the completed part of the original project and the other, the remaining part. These two parts are made subprojects of the original partially completed project, and their names are derived from the original project's name by appending (1) and (2) respectively.
Don't reschedule partially complete projects : Selecting this option will cause the schedules of partially completed projects to remain as is.