Are you certain it is night terrors? My son is 6 and has night terrors. When he was a baby it was hard for me to tell what it was, but as he grew and I talked with his pediatrician about his symptoms, this is what he was diagnosed with. It is like sleepwalking where they seem like they are awake but they are not - different from waking from a bad dream or something. My son did have night terrors more regularly when he was younger, but now it is the classic symptom of him crying in his sleep once per night about an hour after he falls asleep(he even sits up with his eyes open at times and can respond to my questions but he is asleep and never remembers the episode). The episodes are few and far between now. The last time was about 4 months ago. My nephew also had night terrors and fully grew out of it by about age 7. How tired the child is also affects the night terror. When my son is overtired is usually when he will have one.
So, what to do about it. What we were told by his pediatrician and what we do works fairly well, which is NOT trying to wake him up. That prolongs the terror/makes it worse. We know because we tried this for awhile before we realized that it was night terrors. All we can do is try to help him fall back into a restful sleep. I also realized that the more I verbally talk to him, it seems to make it worse. I may say, "you're okay" and "I love you" but not much more. My son always sits up now when he is having a night terror, so the first thing I do is help him to lie back down as he can't seem to figure that out on his own. Then I lay next to him and/or rub his back or hair. Sometimes too much touch irritates him more though. It is a little different each time.
Good luck! Night terrors are hard to deal with. Oh - another thing the Dr. suggested is to time when the terrors occur throughout the night and wake him up right before to head off the terror from happening. This technique was hard for me because I hate to wake a sleeping baby/child. But, that is worth a try too.