You can use the feature of Qlik Sense that was introduced in Qlik Sense June 2017 called Advanced Analytics Integration. AAI has it's own forum site her on Community: Server Side Extensions (SSE)
R and Python were the first languages that had full examples on how to integrate with. There are lots of videos and documentation on how to do it at the forum site.
The integrations are released as open source even though the basic communication feature that ties directly into the expressions in Qlik Sense are generic (Server Side Extensions).
Link to Github and the Python AAI: GitHub - qlik-oss/server-side-extension: A Qlik server-side extension protocol for extending the Qlik built-in expressio…
One important thing though is that the AAI is focused on getting data integration first and foremost. So you will not find examples I believe on bringing graphs/plots over with the AAI. There shouldn't be a problem implementing it though - but it wont be out of the box.
Anyway if the plot is something you can use the charts in Qlik Sense instead it will be easy to transfer the dataframe and do the graphing in Qlik Sense.