i would NOT use nic-a-date...
although it will probably make the date visible again - it will also leave an unsightly "burn" mark.
if you want to try to reveal the date...try letting it sit in white vinegar. it can take anywhere from a couple of days, to a couple of weeks, and will leave the coin with a dullish grey appearance, and isn't guarantted to make the date reaqdable, but it is preferable (in my opinion) to nic-a-date.
i have done this with several
Buffalo nickels, this pretty good success..