A. 1. Before updating the app, back up your data if the app provides an export feature. 2. After an update, check the app's settings for any options to restore or recover lost data. 3. If data is missing, check if the app has a cloud backup feature that may have saved your historical data.

B. 1. If historical data is lost, consider reaching out to community forums or user groups for the app to see if others have experienced similar issues and found solutions.