Прибавить часы к значению в ячейке

Sub Copy_2()
    Dim xCell As Range
    Dim xStr As String
    On Error Resume Next
    lngZ = Cells(Rows.Count, 2).End(xlUp).Row + 1
    For Each xCell In ActiveSheet.Range("B1:B" & lngZ).Cells
        xStr = Trim(xCell.Value)
        xCell.Offset(0, -1) = Left(xStr, InStr(xStr, " "))
        xCell.Value = Right(xStr, Len(xStr) - 5)
    Next
    For Each xCell In ActiveSheet.Range("A1:A" & lngZ).Cells
        xCell.Value = xCell.Value + TimeSerial(4, 0, 0)
    Next
End Sub

    Dim xCell As Range
    Dim xStr As String
    Dim timePos As Integer
    Dim timeStr As String
    Dim newTime As Date
    On Error Resume Next
 
    For Each xCell In ActiveSheet.UsedRange.Columns("B").Cells
        If xCell.Value <> "" Then
            xStr = Trim(xCell.Value)
            timePos = InStr(xStr, ":")
            If timePos > 0 Then
                timeStr = Mid(xStr, timePos - 2, 5)
                If IsDate(timeStr) Then
                    newTime = CDate(timeStr) + TimeSerial(4, 0, 0)
                    xCell.Value = Replace(xStr, timeStr, Format(newTime, "HH:MM"))
                End If
            End If
        End If
    Next xCell