Button formula to force a "reset" of snapshot field.

I have a parent table - Customers - there is a field for Sales tax rate. This rate can change periodically, so in my Charges table (that looks up the Customer) I am looking up the sales tax rate from the related Customer and then placing that value in a snapshot field. Charge calculations then use the snapshot field for the tax rate that way, if the Customer rate changes, historical charges will still be correct.

From time-to-time, new Charges are created before the Customer tax rate was modified, so now the new Charges are out-of-sync with the correct value. The only way I know to correct this is to edit the charge, remove the customer link, save and keep working, then reselect the customer.

Is there a way to build that logic into a button that would accomplish the same thing? Essentially turning 5 clicks into 1?