I would definitely send the form in every time it drops. That's the main reason I chose the Early Saver rate so I would be protected up until 2 business days before sailing. Heck, I would send the form in if it was only $5 difference. That was the deal in exchange for it being a non-refundable deposit. Plus, it was a substantial discount.
There is another thread here
with some links I posted for information.