A repeat client is a client who hires the same freelancer or agency again on a new Upwork contract after an earlier one ended, a pattern Upwork states counts in favour of the Job Success Score.
A client who wants to work with someone again can rehire them from the closed contract, which opens a new contract with the same parties and no proposal or Connects needed. The new contract has its own feedback and its own line on the work history, and Upwork marks it so that readers can see the client has hired before. The number of such clients is one of the clearest signals on a profile, because a client who comes back is voting with money rather than stars.
Upwork's description of the Job Success Score names repeat clients and long-term clients as things that help the score, without saying by how much; the weights are set by Upwork and not published. The reasoning is that a return hire implies the previous contract went well, whatever the feedback said.
Two points are often misunderstood. First, a client who keeps one contract open for years is a long-term client, not a repeat one; the distinction is whether a contract ended and a new one began. Second, repeat business is counted per client account, so an agency whose several contacts at the same company each open contracts is seeing new clients in Upwork's terms, not repeats. Working with the same client off Upwork to avoid fees is circumvention, and Upwork's Terms of Service forbid it.
How Upwork Insights uses it
This term describes Upwork's own rules or product rather than a figure the index measures; the pages that do carry live figures are the stats and rate pages.