A good way to easily duplicate the project if you still have the files is by doing the following
Backup the folders before messing with them just in case a mistake happens to avoid corruption
Open the .uefnproject with any text editor
Replace all letters & numbers in the following fields with 1 and then save them
Then inside Project Browser Press browse and find the .uefnproject
Then you’ll be prompted to either Press “No,Leave as is” or “Yes, Change Project”
Pressing “No” will just load it without the ability to launch into fortnite or any kind of urc and probably other features missing
Pressing “Yes” will duplicate it and make a new project in your creator portal.
Again since fortnite banned your previous project I’d recommend making super duper sure that your island does not break any rules because next rejection might trigger a creator code ban or something equally severe. hopefully this helps you “open & investigate” your project for any offending materials they might’ve mentioned in the rejection