clearing a sub menu of items?

I have a menu item that shows a list of file located in a directory. If I add or delete delete one of these files in the directory , and try to refresh the menu, it doesnt change. how would I go about doing this?

here is my current code
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Code:

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Private Sub RefreshGroups()
Dim myArr() 'to hold the file names
Dim stFile As String
Dim idx As Integer
On Error GoTo Errortrap
stFile = Dir$(DataDir & "*.grp*") 'get all text files
idx = 1

Do While stFile <> ""
ReDim Preserve myArr(1 To idx)

mnuBarGroups(idx).Caption = stFile 'use the file name
stFile = Dir
idx = idx + 1
Loop

Errortrap:
Load mnuBarGroups(idx) 'build the menu
mnuBarGroups(idx).Caption = stFile
Exit Sub
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Private Sub mnuBarGroups_Click(Index As Integer)

    Dim fname As String
    fname = DataDir & mnuBarGroups(Index).Caption
    If fname = DataDir Then
    Exit Sub
End If
    Open fname For Random As #2
    Dim contents As record
    Dim X As Integer
'Adds each user in the file to list1
    X = 1
    Do Until EOF(2)
        Get #2, X, contents
        List1.AddItem contents.userid
        X = X + 1
    Loop
    Close #2
End Sub
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Thanks!
Garrett