To duplicate projects with recurring phases, in the List View, go to the Frequency field and choose either Monthly or Weekly. This choice will create a new phase, copying the previous one.

For example, if you choose Weekly, a new phase will be made a week before the previous one starts. With Monthly, the new phase lines up with the next month. To stop this recurring pattern, simply clear the Frequency field in the final phase of its kind.

Also, see the official training course on How to Customize & Manage Timelines for more information on creating a recurring project.