For ranking on the leaderboard, points are accumulated for two months. Old points expire so new people can have a chance to get on the leaderboard. It keeps you working hard :) Your total accumulated points are not lost---they are just not used to calculate the rankings. If you check-in everyday and click on "check in" on the website, you also accumulate check-in points and I don't think that one expires. If plenty of people request the feature to display the problem-solving points, we will consider adding more display boards in the next major upgrade of the site.
Monthly Contest registration for the next month is open each month around the 15th. This month because the Areteem Online Summer Camp is going on, it might take a couple more days to set up the Monthly Contests.