Option Explicit
Private Sub CommandButton1_Click()
Dim M As Integer, J As Variant, Sh As Worksheet
M = 0
For Each Sh In Worksheets
If Sh.Name Like "BL*" Then
J = Mid(Sh.Name, 3)
M = WorksheetFunction.Max(J, M)
End If
Next
If M > 0 Then
M = M + 1
Sheets.Add(After:=Worksheets(Worksheets.Count)).Name = "PLIS" & M
Sheets.Add(After:=ActiveSheet).Name = "MAN" & M
Sheets.Add(After:=ActiveSheet).Name = "BL" & M
End If
End Sub