Make a backup without Media (This ignores the Export’s complication of filters.)
Then Add a new tree and import. This gives you a fresh Tree… I usually rename it to include the date as part of the name.
But you might want to use that fresh tree for your main one and experiment in the old one. That’s because the fresh import will have the cleanest database structure… basically like doing a defrag on your storage device.
Please note, the working tree is a database (MySQL SQLite, by default). XML is archival format, not the working format.