Sub test()
Dim sheet_count As Integer
Dim sheet_name, new_sheet_name, old_str, new_str As String
sheet_count = ThisWorkbook.Sheets.Count
old_str = "A15"
new_str = "A02"
For i = 1 To sheet_count
sheet_name = Sheets(i).Name
'MsgBox InStr(sheet_name, old_str)
new_sheet_name = Replace(sheet_name, old_str, new_str)
MsgBox new_sheet_name
Sheets(i).Name = new_sheet_name
Next i
'MsgBox sheet_count
End Sub