All you can really do about these is to chimp early and often, and possibly shoot bursts if the camera allows, so that you can at least get a shot even if the strobe ruins it.
Lasers: take precautions!
Be very very careful never to shoot directly at a laser beam coming at you. This is a very easy way to damage a digital sensor.
Flash is your friend
If your camera has a flash hotshoe, then it may be worthwhile to save up the pennies, or campaign for your yearbook committee to get a hotshoe flash (or speedlight) for the camera. It doesn't have to be expensive, but you'll probably want one with TTL and HSS capability, if your camera supports those (see: What features should one look for when selecting a flash?). You definitely want one with tilt and swivel capability.
And then practice with it, and learn to bounce it. Basic on-camera flash technique can go a long way to elevating your photography, and helping you out in low-light situations. But you are going to have to relearn how you think about exposure and exposure settings.
Basic low light
Obviously, you're probably hoping to get as high a shutter speed as possible to avoid some motion blur, so using a fast lens with a wider-than f2.8 maximum aperture can be a huge advantage, as well as mastering your AF technique in low light (a flash can also help here, with an AF assist beam). But you may also want to boost your ISO up into the 1600 and above range, depending on the camera's ISO performance. A tripod might help, if you don't mind blurring the dancers' movements.
Basic Event think
Event shooting is all about planning, preparation, and anticipation. Know what the lighting is going to be, and how to handle it. Know where the people are going to be, and what they're likely to do when. Go to rehearsals for the lighting/music setup if you can, find out the set lists, any special effects plans that are going to happen when. Be there before it happens. Anticipate, anticipate, anticipate.
You may also want to consider backup gear, so that if something goes wrong with your flash, camera, cards, lenses, batteries, etc. you don't end up without any images at the end of the dance.
Don't think, however, that a completely blur-free image is necessarily the goal you always want. Playing in low light with light sources can be a great deal of fun, and you could approach this as light-painting opportunities, and a chance to try out a flash with second-curtain/slow sync and other motion-blur techniques, like zooming while taking the shot.