To print a receipt from a transaction after you've completed it, you may do so from your Transactions List.
The Transactions app may be accessed from either the left-hand menu in Terminal, or directly from the Home screen.
Once in the Transactions list, simply slide across on the transaction of which you'd like to print a duplicate receipt.
Select Receipt to print that receipt.
NOTE: Options on reprinting receipts is tied to Receipt options setting (Account & Settings --> Store Settings --> Receipts --> Receipt Options). For example, if only Email and SMS receipts are enabled, those are the only two options that will be available to reprint a receipt. Confirm that Paper receipts option is enabled in order to print a paper receipt.