When I accidentally delete something I'm writing (say, in an email), is there a way to recover it on the iPad one?

If you catch it right away - and I mean right away - there is an Undo bottom on the keyboard. If you tap the ?123 button in the lower left corner, that will bring up the Undo button. Try that next time.

That has worked for me from time to time. And yes, shaking the iPad will bring up an Undo Typing box as well.

This worked with my iPhone, thank you!

No, not unless you selected and cut text. If so, you can use the paste feature to restore the cut text.

Have you tried shaking your iPad?

(seriously.)

A prompt asking you to undo typing should come up in a blue box

Yelling at it doesn't work then 😕