Hopefully she’s wearing this costume from the movie, or maybe one we didn’t see before in the finished film?
I didn’t mind the other outfit, it showed she was not having any of the trappings of royalty and could relate to the troops. It also echoed her Hoth outfit in Empire.
There are so many ways now that they can digitally manipulate the Leia footage, (while preserving Carrie’s performance) I doubt integrating it into new sequences will be a major problem.