The good old Australian Anglican Prayer Book (AAPB) has some great prayers written in it for various things on pages 91-97 (also p.120). Doing some of these every now and again is a good way to be trained in WHAT to pray and different things to pray for. The leader of the prayer time can print some off (or photocopy) a few of the different prayers and choose some of the youth group to pray them out. Some of the language might need to be adjusted and updated so the youth group understand it.

Here is a word document of the AAPB prayers with language adjusted to be gender inclusive.