Import simply does a one time creation of the list. If you want an Excel sheet
linked to the list  for making future updates, you'll need to export a new
spreadsheet from the list and make your updates there.

Or, if you have Office 2003, you can use the Export and Link to Excel
option that's available from the Datasheet View of a list  (in a task
pane that is hidden by default on the right hand-side of the datasheet!)

Once a list is linked you can use the List/Synchronize option in Excel
2003...

Thanks for the help  guys.
Let me explain what exactly I am loking for.

I have an excel spreadsheet  which gets data  from our AS400 database.
This AS400 refreshes the excel  sheet and puts new data into it
everyday. I want to display the excel spreadsheet on the Sharepoint.

I have tried using the import  Spreadsheet but it will not refresh
itself with the new data being added to the excel sheet.

I can use the Datasheet view of the List, but how do I link it to
ane existing excel sheet? the datasheet view only allows me to
export to an excel sheet. It does not allow me to import an existing
excel sheet.

Is there any other means or webpart which will allow me to publish
an excel sheet on the sharepoint  and refresh  it with new data when
the excel is appended with new data??

Is viewing of the spreadsheet  your only goal, or are you looking to do something
else that requires the data  to be in a sharepoint  list?

If it's the former, you can just copy the xls file directly to a SharePoint
document library - there are several ways to do this, but the easiest is to use
WebDav.

If it's the latter, is there any option to have the AS400 process create
something other than a file? If so, you could have it write directly to the
sharepoint list  web service...

That's actually part 2 of what I was suggesting..