Here is a script to automatically preserve your form posts in their own "Flash Data" type of thing. Set it up in 3 steps. I searched all over and couldn't find this built in yet, if it is I would love to know!

So basically after this, all you do is place <?=formData('field')?> or {{ formData('field') }} in your input value container.

Let me know if you find flaws, I whipped it up in an hour.