How to deal with repeated resubmissions of a bad paper (as a reviewer)?
This type of repeated submission of junk is something that I truly hate, but also don't know any good way of dealing with.  The problem is that the same freedom that supports novel science also leaves room for this type of "publication-shopping."  In essence: any more unified method of "disapproving" junk papers, to prevent them from wasting everybody's time, will also work against highly novel papers that are meeting resistance from entrenched communities---see, for example, the decades-long fight Barbara McClintock faced in getting her work on gene regulation accepted.

We are thus left with the current and default system, in which each publication judges independently, and in which reviewers face frustrating situations like the one you describe.  My recommendation, then, is simply to judge the paper on its merits, of which it has little.  The biggest key strike is the self-plagiarism: once you've discovered that, the rest doesn't really matter, because self-plagiarism is an offense worth rejecting a paper over in and of itself.  

I would recommend informing the editor, along with informing the editor about the history of the paper.  They may then either judge whether to speedily reject the paper (and possibly initiate proceedings against the authors for the self-plagiarism), or whether to ask you to formally write this assessment as a review.