I use a little Ruby script:
r=File.open('read from this file.svg').read
r.gsub!('id="path', 'id="Territory_')
File.open('write to this file.svg', 'w').write r
Copy that, save as something.rb, change the filenames, copy to directory containing the file and run. You must have Ruby interpreter installed (any version) - it's free. You can get it here:
http://rubyforge.org/frs/download.php/47082/ruby186-27_rc2.exe (25 MB).
It only works if objects already have "path9999"-format ids - but it seems they always have. Also, it will convert every single path to territory - you might have to change some ids back.
Hope you like it :D