Lightroom's exposure adjustment has a range of -5 to +5 stops. You can exceed that limit by using an adjustment brush. You can paint the entire screen with a large brush or apply it to any portion of the image as usual. The effect of the adjustment brush is cumulative and you can apply it more than once.
Note: Of course, this only makes sense if your camera captured detail in the first place. This won't magically bring back clipped details.