Remember that the updater is not aware of this level, so it will probably overwrite it.
indeed, I've had trouble with this so I always take a backup, just rename the original first and put this in, then when you need to update rename the fix to something else and the original back to normal so the updater will skip it, and not download it again :p.
For linux users, just copy paste this into a new sh file, place the sh file in /path/to/planeshiftfolder/art/maps
mv bronzedoors.zip bronzedoorst.zip
mv bronzedoorstemp.zip bronzedoors.zip
mv bronzedoorst.zip bronzedoorstemp.zip
for windows users place these lines in a new .bat file and place the file in c:\path\to\planeshiftfolder\art\maps
rename bronzedoors.zip bronzedoorst.zip
rename bronzedoorstemp.zip bronzedoors.zip
rename bronzedoorst.zip bronzedoorstemp.zip
I don't know what you do in mac, but just remove the command for mv and replace it with the macs rename command xD
run the sh/bat file now before you download, and run it again before you update
after the update run this file again