When an experiment decision has been made and there is a need to continue collecting metrics without resetting user assignments, the platform does not offer a native solution to directly address this scenario.
Once a decision is made on an experiment, the platform does not support undoing that decision. The 'Reset' option is available; however, it will revert the experiment to an unstarted state, and all users will receive the default experience. If the experiment is reset or a new experiment is started, users will be randomly assigned to a group, which may differ from their original assignment.
It is important to note that resetting an experiment will not preserve the initial user group assignments, which may be critical for long-term metric collection and analysis. To monitor the performance of long-term metrics after an experiment has ended, the Metrics Explorer can be utilized. While it does not provide confidence intervals and p-values, it does offer absolute numbers for each metric across all groups in the experiment.
For future experiments, it is recommended to enable Reviews in the project settings to provide better oversight and prevent similar situations. Reviews offer guardrails that can help in managing changes that impact production environments.