There is no problem with recarbonating the beer, so don't worry about that.
Unless you have a leak in your system, the beer will not lose any carbonation it already had. That's not to say that it's fully carbonated. Rather, it got as far as it did before the tank ran out, and then it stopped. It did not backtrack.
Speed carbonating at high pressure is a bit tricky in that it leads to unpredictable results. Typically, though, it leads to overcarbonating the beer. Once you get your tank refilled, I recommend hooking it back up to the keg and pouring yourself a sample at the serving pressure. Just see where you are before you take any other steps.
If you think the beer is undercarbonated, take the keg out, change the gas line fitting to a liquid line fitting, attach the gas line to the liquid post, and shake or roll the keg around (at the "set it and forget it" PSI) until you no longer hear CO2 bubbling up through the beer. That'll get you nearly all the way toward your desired carbonation. Then, remove the gas line from the liquid post, switch the fitting back to the gas fitting, reattach the gas line to the gas post, put the keg back in the fridge, and chill out. With the couple days you have until the Super Bowl, you should nail your carbonation. If not, you'll be very close. It'll all be good.
I "speed" carbonate all my beers by the procedure in that last paragraph. It saves me a few days waiting or more without overshooting the carbonation I wanted in the first place and going through all the mess to get it back where I want it.
TL
