How do I reprint a letter?
Letter bundles are only downloadable and printable when they're in the "Unprepared" column on your dashboard; this is where they go when you first "adopt" voters.
To return a letter to that column so you can download and print it, use the left-facing, arrow button on the letter bundle you want to move to shift that letter from your "Prepared" column to your "Unprepared" column, where you can download and print it again.
Individual letters within a bundle can be downloaded even if the bundle they are within is in the "Prepared" column. So if you just need to reprint one of them, there's no need to move the bundle between columns.