In order to enable restarting a conversation in your web chatbot, you need :
1- go to Publish > Design then select Chat window and click on the circular arrow.
2- Make sure “Activate the relaunch button” is checked.
3- select the bubble that should be triggered on restart.
4- (optional) in Publish > User behaviour management, you can select the “Delete conversation on restart” option if you want to clear the conversation on restart.