VBA to duplicate cell and continue numbering

Is there a code that will duplicate/insert a new row and continue the numbering system that is in column A. In the attached example I use the following code to duplicate the row that is above the cell that contains the letters "BO". In column A I have a numbering system for each row; ie SU-1, SU-2, SU-3, etc. I would like to click the button and add a new row and to contine the next number in line. So if the last row was SU-9, i would like the new row to = SU-10.

Sub StartUp_Click()

r = Columns(1).Find("BO", LookIn:=xlValues, LookAt:=xlWhole).Row
Rows(r - 1).Copy
Rows(r).Insert
Application.CutCopyMode = False

End Sub