Besides using the brightness/contrast filter, you can adjust HSL (hue,saturation and luminance. These are all part of the Video FX feature. A litter adjustment goes a long way. Trying to over correct isn't the answer. If you have version two, there are many easy to apply presets. If you want to do it by hand try adjusting lumiance to between 1.04 - 1.10 for starters. Adjusting brightness and contrast generally goes in opposite directions. If the night scenes are just a little dark, I would try 1.10 on brightness.

If only some scenes are dark, then apply the correction just to those scenes to avoid over correcting the whole video.

Spend a few minutes reading the manual or help for more detailed how-to as far as selecting scenes which are referred to as "events" on the timeline.