You say that you have to do this a lot in the future. So try this:
When your project is finished and you no longer wish to edit it click on FILE - PACK PROJECT MATERIALS. This action saves the project itself (.PDS file) and all the material in your project in its original form eg .mp4, to a folder of your choice. So all your separate clips will be visible in the folder you chose.
When you wish to import the clips back into a new worspace you can do the following:
Open a new workspace in PD, then open Windows Explorer and go to the folder where you packed the project to. You will be able to see all your clips to identify them plus the project in .PDS form.
select the first clip you want to use again and then put your finger on the CTRL key and keep it there. Start selecting all the other clips you require until they are all highlighted. then, still keeping your finger on the CTRL key drag all the clips at once into the new workspace you opened in PD.
This should make life easier for you
Robert
Panny TM10, GH2, GH4,