If you are on Linux or other unix, you can use my script to rename pages on the command line.
#!/bin/sh
# Author: Simon Kaczor <skaczor at prognosoft dot biz>
# Renames a dokuwiki page to a new name name and/or namespace. Script
# should be run from the data/pages directory of dokuwiki
# installation. Do not include the ".txt" extension in page name.
#
# Known limitations:
# - Doesn't try to find and fix backlinks.
#
if [ $# -lt 2 ]
then
echo "Usage rename-dokuwiki-page <from> <to>"
exit 1
fi
page=$1
new_page=$2
mv -v $page.txt $new_page.txt
pushd ../meta
mv -v $page.indexed $new_page.indexed
mv -v $page.changes $new_page.changes
mv -v $page.meta $new_page.meta
pushd ../attic
for file in `find . -wholename "./${page}.*.txt.gz"`
do
dest=`echo $file | sed -e "s,$page,$new_page,"`
mv -v $file $dest
done
popd
popd