Sure, you can use nintex o365 rest api‌ and the method "Import into a new workflow": http://help.nintex.com/en-US/sdks/sdko365/#Reference/REST/NWO_REF_REST_ImportWorkflowPost.htm%3FTocPath%3DNintex%2520Off… 

This should work for you

Regards

Thats Great!! Tomasz. 

Could you also suggest, how can we get the Workflow ID. I can see ID is mandate in the REST API for exporting the workflow

Its easy

1. export  the workflow manualy,
2. open the file with 7z or WinZip (It's an archive),
3. go to the metadata.xml file,
4. open it and there you will find workflow guid 

 Easy, isn't it? Now you can use it in your workflows. 

 Regards, Tomasz

You saved my day Tomasz!! Thanks