sed or awk would be the fastest way. I’m not enough of an awk master to give you the command but awk will do it with a carefully crafted command line. In sed, try something like:
sed "s/0.00 /1.00 /g"
on all your filenames. (This will also set your B-factors to 1; you can learn sed/awk and regular expressions if you want to change only the occupancies column.)