remplacer valeur

=GAUCHE(A1;NBCAR(A1)-2)&B1&DROITE(A1;2)

Sub test()
Dim Info1 As String, Info2 As String
Dim Résultat As String, Portion1 As String, Portion2 As String
Info1 = Range("A1")
Info2 = Range("B1")
Portion1 = Split(Info1, "~~")(1)
Portion2 = Split(Info1, "~~")(2)
Résultat = Replace(Replace(Info1, "~~" & Portion1, "~~" & Portion1 & "~" & Info2), "~~" & Portion2, "~" & Portion2)
Range("C1") = Résultat
End Sub

=SUBSTITUE(A1;"~~";"~"&B1&"~";2)

Sub Macro1()
Dim ligne As Double
ligne = 1
Columns("A:A").Insert Shift:=xlToRight, CopyOrigin:=xlFormatFromLeftOrAbove
While Cells(ligne, 2) <> ""
    Cells(ligne, 1).Select
      ActiveCell.FormulaR1C1 = "=SUBSTITUTE(RC[1],""~~"",""~""&RC[2]&""~"",2)"
      ActiveCell = ActiveCell
      ligne = ligne + 1
    Wend
    Columns("B:B").Delete
    Columns("A:A").EntireColumn.AutoFit
End Sub