Undo remove word from autocorrect

In the newest versions of Android, you can click and hold a suggested predictive/autocorrected word, and drag it into a bin (title "remove") to prevent it from being suggested again. I accidentally deleted the word "I", so now when I type "i" it doesn't automatically autocorrect to "I". Two related questions: 1. I tried shaking my phone to undo the accidental word removal (like I would undo things on an iPhone), but it didn't do anything. Is there a way I could've undone my action immediately after it happened? 2. Now that it's a few days after the face, how to do I add "I" back to the suggested words without having to completely erase all the things my keyboard has learned about my typing habits?