@spottedsparrow: Yes, if you update the description, and the
"Turn On Manual Edit of Meta Title/Description/Keywords/Abstract (Global)"
option is unchecked / off, then it will update on it's own.
If
"Turn On Manual Edit of Meta Title/Description/Keywords/Abstract (Global)"
is checked / on, then it always pulls from that admin form field. If you want the override to re-generate/re-populate the data in the admin form field, then you have to clear the field desired to re-generate and then save the form. Upon re-entry of the product admin form, the data will repopulate. Again, this is only for if you are using the override (checked) option.