A reinitial is a member that has downgraded from a paid subscription to a basic membership, then re-upgraded (after any period of time) to become a full paying member (initial) again. Reinitial revenue is the revenue generated through this action.
Your reinitial member count within the key metrics report is the number of members that have downgraded to a basic membership from a paid subscription, then re-upgraded to become a full paying member again. You can view this data with preset or custom timeframes.
Understanding reinitials is important as it will mean the lifetime value for a member will increase. The reinitial revenue associated with a member that re-upgrades can be linked back to your marketing campaigns and is likely to impact the amount you can afford to spend on acquiring a member.
In order for your campaign tracking reports to generate accurate, useful data, you must ensure the White Label Dating campaign tracking script is installed in your landing page code. If you are using the WLD design tool to create your landing pages, this will already be present. If you are using a custom-built landing page, you (or your developer) will need to add this code manually.
More metric definitions can be viewed in summary here.