5. Make it Personal
This is another way to up the stakes. Now, Im not suggesting that the aliens return to Earth simply with the intention of killing Jeff Goldblum, Will Smith or Bill Pullman, that would be much too ridiculous. But give the story a more personal spin. Have someone close to these three main characters (a wife, a child, a known relative - Im looking at you, Judd Hirsch) get killed by the aliens upon their arrival. Look, if Independence Day 2 takes place years after the original film, than our three key characters are going to be significantly older than they were in during the first go round. Their best alien fighting days will surely be behind them. By killing off a character close to them, it gives them a reason to get back into the fold. That makes everyones investment in the battle just a little bit more intense, and draws the audience into the struggle even more.