Step 1: In your "Jobs" tab, click on the drop-down menu of the job you'd like to duplicate. 

Step 2: The duplicate job is put into your draft section with "copy" added at the end of the title.

Step 3: From here just edit the job as per usual to make it just right to promote and start collecting highly-qualified candidates. Just click on the drop-down menu on the far right and select "Edit Job".