Not a straight forward question.

And I imagine that the person who gave you a precise % in the answer above mine is full of hot air as your question cant be answered that way.

You use the word ‘expect’ but surely you mean ‘aim for’. Even then context and strategy mean the % can vary hugely.

Eg it would be a smaller number if you have many competitors locally who actively try to lure away clients with discounts for the first job.

It would be a smaller number if you didnt focus on excellence in customer service and have good retention strategies in place.

It would be a bigger number if your clients were companies with complex marketing needs who would be reluctant to switch to a competitor due to the costs/risks involved in having to start over.

It would be small if your clients tended to be people who use a marketing firm for rare special projects.

I hope these simple examples give you an idea of the issues behind your question.

Why do you need a %? If you explain that you may get more useful answers.