Tu as juste à l'ajouter après le calcul de DerLn :
Private Sub Worksheet_Activate()
Application.ScreenUpdating = False
Application.EnableEvents = False
Range("A5:G" & Range("A" & Rows.Count).End(xlUp).Row).ClearContents
With Sheets("Etape 1")
DerLn = .Range("A" & Rows.Count).End(xlUp).Row
If DerLn = 0 Then Exit Sub
For i = 6 To DerLn
.Cells(i, "B").Value = i - 5
Next i
Set Plage = .Range("A6:G" & DerLn)
Plage.Sort key1:=.Range("C6"), Header:=xlNo
For i = 5 To 13
.Range("A" & DerLn & ":G" & DerLn).Copy Cells(i, "A")
Cells(i, "B").ClearContents
DerLn = DerLn - 1
Next i
Plage.Sort key1:=.Range("B6"), Header:=xlNo
Plage.Offset(0, 1).Resize(Plage.Rows.Count, 1).ClearContents
Cells(1, 1).Select
End With
Application.EnableEvents = True
End Sub
eric