If your printer is not functioning correctly, ensure that it is plugged in and powered on, that there is paper loaded, and that there are no foreign objects in the paper compartment.
Exit the Shopwave app and open the main settings screen for your iPad. Select Bluetooth and ensure that Bluetooth is switched on.
Ensure that the iPad is connected to your printer. The device list should contain a device called 'Star Micronics' if this hasn't been changed and next to it, it should say 'Connected'.
If it says 'Not connected', tap this to re-connect the device. If this does not work, tap the 'i' icon and select forget device. Now re-pair the device as per the instructions here: https://getshopwave.zendesk.com/hc/en-us/articles/201906912-Bluetooth-Printers-Getting-started
If the printer is connected and you are still unable to print, exit the Shopwave app and shut it down by following the instructions at the following link: http://support.apple.com/en-is/ht5137
Then launch the Shopwave app, log in, and try printing again.
If printers constantly disconnect, check that you have auto connect on by downloading the Star Bluetooth Utility App. If it is is not turned on, follow the steps below to activate: