Try this. You'll want to move your Add button up above the data.
Private Sub Add_Row_And_Worksheet_Click()
Dim rw As Long, sname As String
Application.ScreenUpdating = False
rw = Range("B3").End(xlDown).Row + 1
Rows(rw - 1).Copy
Rows(rw).PasteSpecial (xlPasteFormats)
Application.CutCopyMode = False
Cells(rw, 2).Value = Cells(rw - 1, 2).Value + 1
sname = "REF" & Format(Right(Cells(rw - 1, 3).Value, Len(Cells(rw - 1, 3).Value) - 3) + 1, "00")
Cells(rw, 3).Value = sname
With ActiveWorkbook.Sheets("Master")
.Visible = True
.Copy after:=Sheets(Sheets.Count)
.Visible = False
End With
With ActiveSheet
.Name = sname
.Range("A2").Formula = "=Summary!B" & rw
.Range("B2").Formula = "=Summary!C" & rw
.Range("C2").Formula = "=Summary!D" & rw
End With
Sheets("Summary").Activate
End Sub
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