Oups, fill in a bug report: http://dev.tikiwiki.org/tracker5
This is a serious usability issue.
Are you using latest stable tiki (2.0)?
In the meantime, I would say, try adding an "alias" for that page through structures, or just made a page with the new name which "redirects" to the old one with comments. (see PluginRedirect ).
While you can get attention by a coder to fix that... (if in a hurry, you can offer some money to have that fixed: main developers might be very busy with other stuff with higher priority to them - See Consultants - I'm not a coder, btw).
And welcome to Tikiwiki Community!