Sub dslkj()
For Each sl In ActivePresentation.Slides
    For i = 1 To sl.Shapes.Count
        If sl.Shapes.Item(i).Type = msoLinkedOLEObject Then
        'Debug.Print sl.Name & "-" & i & "-" & sl.Shapes.Item(i).LinkFormat.SourceFullName
        sl.Shapes.Item(i).LinkFormat.SourceFullName = Replace(sl.Shapes.Item(i).LinkFormat.SourceFullName, "xlsx", "xlsm")
        End If
    Next i
Next
End Sub