Sub Demo()
Dim iShp As InlineShape, strTxt As String, Rng As Range, sWd As Single, sHi As Single
strTxt = "Alternative Text"
With ActiveDocument
  For Each iShp In .InlineShapes
    With iShp
      If .AlternativeText = strTxt Then
        sWd = .Width
        sHi = .Height
        Set Rng = .Range
        .Delete
        Exit For
      End If
    End With
  Next
  Set iShp = .InlineShapes.AddPicture(FileName:="IMAGE_LOCATION", _
    LinktoFile:=False, SaveWithDocument:=True, Range:=Rng)
  With iShp
    .AlternativeText = strTxt
    .Width = sWd
    .Height = sHi
  End With
End With
Set iShp = Nothing: Set Rng = Nothing
End Sub