Something we're starting to do this year was having Senior "Exit Interviews" with the students gradutating from high school in our church. (Similar to the exit interviews you have in college with the financial aid department.)
We sit down with each senior and walk them through what they can expect mentally, spiritually, emotionally etc going into college. We also ask them how they've grown spiritually over the past four years-- investigating if we are 'achieving' our goal of developing mature Christians and if our ministry was effective in their lives. We also talk with them what it means to still be a church member and in community while they're physically away. We provide them with resources and people to connect them with at their future campus-- already knowing their gifts and interests. We also try to give them an idea of places they can attend church (many students go out of state/town).
This also helps us keep a pulse on them while they are in college and will transition them nicely into our college ministry. We connect each student with an adult mentor/prayer partner from our congregation once in college. From our college ministry we try to transition them into ministry opportunities with other adults in our community especially while they're home on breaks.
But the exit interview provides somewhat of a 'right of passage' that helps draw a line and gives us an opportunity to talk about Christian community and how they fit in the big picture in this different stage of life.
We also do a senior retreat every June that also signifies the 'graduation' from youth group. We also have 'Senior Night' at the end of our ministry year to celebrate them and their involvements and leadership in our youth ministry.