can we save user uttrences to nlu data while they are having a conversation in rasa chatbot to increase the training data?
If you have a tracker store, the utterances are already saved. You can write a program to retrieve them (with intents and entities) and save them to a yaml file for your training data.
how can we do that
In the database that you specified for the tracker store there is a table called events. It has a field called type_name and one called data, among others.
You can select the user events with type_name = 'user'. data is a json from which you can get the text, intents, entities, etc.