If you don't have a backup method, I recommend getting it filled BEFORE empty.
Start looking on Craigslist for a good backup tank...my 5# with which I started my setup is mostly there for backup now.
The 10gram keg chargers are also effective in a pinch, albeit costly. However, they are much cheaper than a new tank!
"We are what we pretend to be, so we must be careful about what we pretend to be."