Preserving Sandbox Changes
You need to ensure that users of your sandbox account understand that any changes they make to a sandbox account after a refresh request is made are not included in the new sandbox. When a new sandbox is activated, these changes, including any edits to custom objects, are overwritten with the data from the chosen source account.
SDF users can save all sandbox customization changes to SuiteCloud projects before the activation of the new sandbox. After activation, the updated SuiteCloud project can be deployed to the new sandbox.
If SDF is not in use, users must save sandbox customization changes in another manner so that these changes are available to be added to the new sandbox account after activation.
For more details, see Sandbox Refresh Impact on Bundles.