Multiple htaccess Using One Ip

I'm trying to figure out a method to quickly be able to adjust my IP in my .htaccess files whenever it changes.

For PHP I simply have one file that includes a global that contains my IP. That file is included in any site where I need my IP. That way, when my IP changes, I can simply change it in that file and all my sites are updated at once.

I'm trying to figure out a similar mechanism for .htaccess, but I'm not sure if it's at all possible.

There doesn't seem to be a .htpassword type of file for IP's or allow/deny blocks. There's no space in .htpassword for an IP. The restrictions almost always apply to subdirectories of multiple domains (like stats or admin dirs) so putting an deny all allow from... in my httpd.conf isn't really an option either.

Any help on this matter would be much appreciated :)