Hello,
Please update the novaPDF version you have to the latest one from our website by following up on this tutorial on how to reinstall the application here:
http://www.novapdf.com/kb/how-do-i-reinstall-novapdf-server-on-client-computers-and-on-the-server-108.html
After updating the application, go to the printers area on your computer right click on the novaPDF printer icon, access printing preferences, in the Page Tab click on the Manage button, scroll down to the middle of the list in the popup window with the predefined forms, Select the A3 form, Click OK and in the Predefined dropdown list from the Page tab you should also have the A3 option available now for you to use.
In doPDF unfortunately this option will not be available.
Thank you.