All users can create unlimited copies of their projects. To create a project duplicate, click the copy button in the project summary bar, as shown below.
Making a copy will preserve all the values, geometries, and changes of the previous file, but in a new project so nothing has to be lost or redone.
Note: If you are missing the copy button on the project management page - it is like you have not completed any analysis (energy/daylight/load modeling). In this case, you will first have to complete the analysis and then create a copy of your project. The copy button appears only when the project has geometry associated with it, and has completed one of the analyses.
How else is the copy feature useful?
Use the copy feature to make a massing study. See how here.
Use existing templates to start your own custom project. See how here.