Sending a notification like this is different from the conversation stuff and there is currently no way to reply such a notification - yet. We have another solution being built and very close to being released. I think that's what you're asking?
We're also going to be publishing some new API methods for conversations (or "messages"), which will allow users to send messages to apps/services which can then reply with a message (if they want). These APIs should be available in the next couple of weeks.