To remind the group or at least get them to think about it once a year. There are a lot of tools to accomplish this, plays mysteries and catechisms are all good tools to educate. The nature of the group will limit how much educating can be done in one ritual. Be aware that there are exceptions. For example the Christian church rarely uses mysteries or plays until Christmas comes then they are used extensively.
Rites of initiation are common to all most all religions.
A ritual of this type should spell out what the group expects from the initiate. The core beliefs of the group and the rules of behavior. A sense of community is very important during a ritual of this type. The ritual should basically remain the same because common experiences build group unity. Groups expect new members to pay dues either before or during the initiation.