One way to do this simply and economically is to have periodic team discussions on questions such as these:
What proportion of our highly valued clients, that is those generating above a specified fee level, are we retaining from one year to the next?
What proportion of our fees comes from new services offered within the last three years?
What proportion of this year’s fees is from new clients?
What proportion of assignments that are pursued this year in competition with other providers have we won?
What proportion of this year’s fees has come from working in new industry, client or geographical sectors?
What proportion of this year’s new clients has fallen into our highly valued client category?
You and your team may find it helpful to formulate annual targets for some of these questions and then to monitor how well you are doing.