You need to reinstall Rome: Total War before installing EB 1.1 ONLY IF.......

....you've installed any mini-mod (apart from EB 1.0) in the main Rome: Total War/data/ directory itself.

EB 1.0 has all it's data stored in a separate sub-folder (called EB), so it doesn't change your main Rome Total War/data/ folder.

But other small mini-mods might have been installed directly into your main folder.

In other words, if your main Rome Total War/data/ folder has been modified since you applied the latest patch, i.e. you've dropped various altered text files directly into that folder, then you'll need to reinstall R:TW from scratch, so you have what's called a 'CLEAN' installation.