In Statsig, you have the ability to both restart and extend an experiment.
To restart an experiment, you can utilize the 'Reset' option. This action will revert the experiment to an unstarted state, and all users will receive the default experience. The "salt" used to randomize a user's group will also be changed. This means that when you start the experiment again, your users will be randomly assigned to a group that is not necessarily the same group they were in prior to the experiment being reset.
When you reset an experiment, it also clears the metrics. However, you will still be able to see the old snapshot in the history, but the experiment itself will start afresh.
To extend an experiment, you can adjust the target duration in the advanced settings. Changing the target experiment length will not result in data loss or change the assignment to Control/Test. The target experiment length is primarily used for tracking progress against your experiment's duration. It does not impact the data collected or the group assignments within the experiment.
Please note that the sizes of variants cannot be adjusted while the experiment is in progress. If you wish to increase the exposure of a variant, you would need to stop the current experiment and start a new one with the desired percentage split.