There is a simplier way than exporting and importing the jar. Lets assume your project is named MyProject123. Just:
- Just open the workspace with your file manager,
- Copy the folder MyProject123 that contains the project and paste it
in an other workspace. - Open eclipse and create a new Java Project named MyProject123
Eclipse will recognize that there is a project with that name in the workspace and will import it. All you have to do is to make refresh (press F5) on the new project.