Well you could import the table in tot Excel to check it, which does not involve the loop.
You could then loop through the Excel Rows and transfer the data.
To update existing records requires different syntax to your current code, you have to use the .edit command.
The syntax takes this form
rs.MoveLast
rs.MoveFirst
recount = rs.RecordCount
For count = 1 To recount
With rs
.Edit
!ShipDate = Me.Shipped_Date
!EquipmentDueBackdate = Me.Shipped_Date + 100
.Update
.Bookmark = .LastModified
End With
rs.MoveNext
Next count
rs.Close
Set rs = Nothing