Remembering things is a limit of the browser, not the site. My browser tends to remember filled-out things on its own when I press back or attempt to reopen a tab, but it also doesn't trigger every time.
If you're on desktop, I recommend the extension Typio Form Recovery. Either way, I recommend uploading a character with an empty profile, and then submitting the profile every once in a while when you're filling it out so it doesn't get lost to mistakes or crashes. You can alternatively work on profiles in a hidden character's profile where you can manually save your progress, google docs where it forcibly saves, or another program with either auto-save or manual saves, and copy-paste it into your profile when it's ready.