You have edited a Project in Premiere Elements (PrE), but want to move some of those Clips to a new Project, but still in an editable format. What can you do, as PrE will not allow one to have multiple Projects Open at the same time, or allow you to have multiple instances of PrE Open at the same time?
The first thought, that usually comes to mind, would be to Select the Clips, then Copy them, close that Project, Open a New Project, and then just Paste those Clips. However, that will not work directly, as the Clipboard gets purged.
One method is to use a Clipboard “extender,” such as ClipMate. Then, one CAN Copy, and Paste into a New Project. I feel certain that there are other Clipboard extenders, besides ClipMate, but it gets very high marks from many users.
Another method, and one that does not involve and additional programs, is to Delete all unwanted Assets from your Project, moving around the remaining Assets, as is necessary, and then doing a Save_As, or Save_As_a_Copy (similar, but different operations - see this ARTICLE for more detail), so as to NOT overwrite the original Project - something that you probably do not want to do.
Then, just Open that Project, and edit, as desired. This can also be useful, when you create a Project, such as an Intro, that you know you will likely use again, but will want the capability to edit it.