Replacing a *.sdlxliff file in a current project in Trados 2015

Dear Collegues,

Today I have been informed by the customer that he has to replace the existing *.sdlxliff file in a current project by another *.sdlxiliff file where have been inserted graphics and other elements. I am working with an existing translation memory and an existing termbase. What is the best way to do this? Can I continue with the current project and only add the new *.sdlxliff file and replace the old ".sdlxliff file or do I have necessarily create a new project.

Thank you in advance

Michael