"If he is returned with a majority in the lower house, how could...

"If he is returned with a majority in the lower house, how could the Senate STILL be refusnicks?"

In almost every case, after a DD they can't, because if it fails to pass they then have a joint sitting of the parliament.

As the government would have more numbers in the House of Reps, they should be able to pass the legislation.

Unless there was some fine balance result there wouldn't be a deadlock after the joint sitting.

Then and only then would there be another double dissolution election.