That's a bummer. I'm guessing you mean an "are you sure you want to leave this page" dialog.
In the meantime, a few tips that might help: If you use Chrome and then right-click on the tab bar and select "Reopen closed tab" (CTRL+Shift+T), it will reopen the tab with the text still intact. That has saved me several times.
It might also help to jot down notes on the notepad on the phone after the punt, while the memory is still fresh. This will give you an easy backup to work from.
And then the third tip that I've been working on is writing shorter, concise reviews. I used to spend forever writing reviews that were like essays, but now I'm trying to write faster, more concise reviews, which are probably easier to read as well.