If you want to keep the paper form and also have the ability to securely generate new passwords:
Buy a cheap, widely, available book (maybe two or three of the same), start at a random page and use the first letters/sentences in this book as your new password. To make it even more secure, I would suggest you add a "standard" to every password you have created ... like "SuperSecurePa##".
So for example: You have bought a book and like to add a new password ... you might start at page one, where the sentence would be: "Once upon a time, there were two developers ..." => this will become your password: "Ouat,twtdSuperSecurePa##"
Even more secure password (due to the size): "Onceuponatime,thereweretwodevelopersSuperSecurePa##"
You can level this up by: - Your chosen appendix has even more "secure" chars, like #*+?="§%&/() (you know what I mean) - You prepend and append your new password with your "common" pass (here "SuperSecurePa##") ... or maybe prepend with a different common pass??