is it possible to get D7 to re-find modules?

I thought D6 did this but D7 doesn't seem to.
I have almost 200 modules in my install but only a small portion of these show at admin/modules.
more info:
- i had a profile installed which had many modules located under sites/all/modules/... but i am trying to run with a different install profile (i dropped in code but did not re-install as i do not want to lose module/site setup) which has many of these modules in a different location (under /profiles)
- even though the modules are listed in the system table (incorrect paths now that they have moved) they do not list at admin/modules
- only modules under /sites/all/modules are listed
since the module is in my system table and in /profiles should Drupal not be able to find it and fix the path in the system table?