Find and Replace
 

I have a worksheet with a column entered based on a list for data validation.
I would like to have the data validation automatically adjust when one of
the items in the list is modified. For example:

The list for data validation includes "Category 1, Category 2, Category 3,
Category 4". The column data of data in question picks from one of these.

If I change Category 1 to "Grouping 1", I would like those cells that
already picked Category 1 to be changed to Grouping 1.

Does anyone know the logic I could start with on this problem?

Thanks.