You cannot edit your responses to your coach after you've sent them. Conversations with your Lark coach are guided — your coach presents reply options and you select from them, so freeform editing is not part of the experience.
If you feel you provided inaccurate information during a check-in, the best approach is to log the correct data directly through the Data screen (for things like activity, weight, or meals) and continue engaging with your program.
Still need help? Contact our support team via the webform at support.lark.com/hc/en-us/requests/new