Renewal Bookings typically refers to the portion of bookings
attributed to existing contracts. The Renewal Bookings is usually taken at the time of the effective renewal date, but might be taken as of the renewal order date (date the renewal order is received or legally binding in the case of evergreen renewals).
When Renewal Bookings is used as a metric for compensation, the metric definition can be complicated. For example, an account manager is singularly focused on renewals. In January, Client A cancels its contract worth $10,000 and Client B renews his contract for $10,000 and upgrades to $20,000 at the same time. The renewal goal for the month was $20,000 and is now achieved even though one of two clients was lost. Naturally this renewal could have and likely should have been recorded as a renewal and an upgrade, but likely only would be if your organization has a well-defined and documented set of metrics.