If you have purchased the tickets from SBB, the counter staff can print a copy, for CHF 5 per ticket. This is not possible at the ticketing machine.
Otherwise the ticket inspector will issue an invoice for travelling without a valid ticket. You can present the valid ticket within 10 days at the counter and will pay CHF 5. Of course, the presented ticket must have been valid at the time of the ticket check for the respective route and travel class.
Kind regards,
Roland