It's one way of saying "I enjoyed this, I had a good time." It just has the obvious meaning. The typical context would be, for example, with friends or work colleagues with whom you were once close friends, who have now moved far enough away that you don't see them all the time. I have a work colleague who was a good friend, whom I saw every day. He and his wife now live 150 km. away. We exchange Christmas cards, email, Facebook postings. Everyone once in a while, once a year or so, we'll visit them, or they'll visit us, or we'll meet for dinner at a restaurant halfway in between. We always have a good time and we always end by saying "We must do this more often."

This means like we should do this again. It can be used in various ways, for example: you and a friend try a new sport or some type of new activity, and you and your friend had so much fun that day, you would say this expression to your friend, "we should do this more often!"

This sentence means that "If you don't get it, we can do this thing many times until you finally know how to do the thing you've learned.". And it depends on the situation when you say this. During class, teacher will say this to make his/her student practice more on the concept. When your parents teach you how to ride a bike or do house chores, they will say this and do things with you over and over again until you get it. Hope that helps!!

You need to write down a bit more about the concept that it was used in, but generally means you did or you are doing something good and now you decide to continue doing that.