I'm not sure why you want to import the images back into Xara. When you create a PDF document, yes you can open and edit it in Xara, but this should not be necessary.

When you create a high quality PDF, you are converting your RGB colors to CMYK which is best for printing or sharing with clients or others.

But you should not try to bring the CMYK images back into Xara. They will look different. Your original images should remain unchanged. Then should you need to edit the document, do this in the Xara document you created and export a new PDF file for printing.