As with anything related to risk, some things don't go to plan, resulting in situations where projects start to run over budget—a problem for you if you are working to a fixed price, meaning you lose money on the project in terms of time and/or costs incurred to complete the work. Although the client's rating would be adjusted to reflect the unexpected time and costs associated with their project, this is only useful for adjusting the price of future work to anticipate the same issues occurring again, and not to recover losses that have already occurred.
There are two options available for situations where a client's project has incurred unexpected costs that have lead to a loss in your profitability or outright loss on the project:
Accept the loss and try not to repeat the mistake.
Attempt to recover the loss.
It is important to remember that freelancers are ultimately in the game to make a profit, hence losing money is a serious issue. Your time also has a value...