Need to create a button to copy the current record details and update a couple of field labels

Wha t I suggest is to not use that approach.

There should be a contract and it should say what period it covers una data entry field.. The Labels in the fields would not refer to a specific year.

Then you can copy the record and change the year in a data entry field. To copy a record, you would use the More ... button to Copy This Record, or else we can help you make a button to do the same thing. Each field on the form has a field property checkbox which indicates if it should be copied when the record is copied. It defaults to yes, copy the field value to the new record.