How change combobox data when the record source on the form is changed

I have a combobox on a form that displays data for all records.  But I also have a command button on the form that changes the recordsource for the form to include only "Completed" jobs.  When that command button is clicked I want the data for the combobox to also include only "Completed" records.  How can this be accomplished?

Here is the code for the command button.

Me.RecordSource = "Select * From tblMoldRepairs WHERE [Completed] = true"