Don't Panic 
Your team won't die out until the last member "dies" out. You are not the first team (no pun intended) to be in this situation, nor the last either. You have two members left, and as long as you keep your nose to the grindstone you will find some way for your team to survive.
Consider this basically starting from scratch for your team. You need to try to accomplish everything that rookies need to go through every year just to survive, let alone thrive. It may be tough, and times may be lean, but if you just keep trying to find more sponsors, members, mentors, and a build space then your team will survive.
Sure, your team may end up building your robot in someone's garage or basement, and you may only have like five students and one teacher. But none of this matters much; just the fact that your team can overcome such difficulties will make whoever joins your team have a much higher appreciation for the team, knowing they played a role in the rebirth of your team.
Here's a few things you might want to consider as you rebuild your team:
- Have the students on the team talk to their friends about the team. It may sound kind of dumb, but if you talk to a bunch of your friends about how much fun and exciting FIRST can be, they may be more likely to join. Once they join, they may talk to their friends about the team, and the exposure of your team will dramatically increase.
- Go out to twenty local companies and ask each one if they would be willing to sponsor your team for $250. It may be a lot of work, but 20 x $250 = $5,000.
- Look for educational grants from the state. These can be real lifesavers for a team getting started. When our team first started, we applied for a $40,000 grant for 1999-2001, our first three years, to help get the team started and off on a sound financial base.