First of all, she keeps bringing herself up. Second, conservatives enjoy the increasing discomfort and disarray she seems to be causing over yonder. Third, the dems keep apologizing for her - either directly or indirectly - demonstrating their inability to shake her. Fourth, obviously, talking about the Clintons does not help the dems.
Actually, she's been pretty quiet over the past 18 months for a major politician who's now retired. Of course she makes some public statements from time to time, but it's Fox News and the right that keep bringing her up, not liberals, as others have pointed out here. The obsession is all on your side, not the liberal one. There is no "increasing discomfort and disarray" about Hillary. She lost the election over a year and a half ago, and is finished politically. She's not going to run for another office, no matter how much the GOP may desperately want her to. The "increasing discomfort and disarray" is actually a much better description of what Donald Trump is doing to Republicans and his supporters, which is just another example of how conservatives love to project their problems and weaknesses onto liberals.
To any objective person it should be clear that the obsession with the Clintons is nearly all on the GOP side. Hell, Fox News can't stop talking about her, even when she's not said anything or is in the news. They actually had a story recently in which they sent a reporter to virtually stalk her in the woods in her hometown in NY. At this point, I don't think the great majority of Independent voters care about Hillary, and bringing her up incessantly isn't going to hurt the Dems as much as you think. You can blame her for everything, but she's not the POTUS, or even holding a political office. It's becoming a dry well for the GOP, but they still can't let it go. Conservatives always need a boogeyman to run against - for years it was FDR, then Truman, then the Kennedys, then Tip O'Neill under Reagan, then Bill Clinton, and then Obama, with Hillary being an all-purpose boogeywoman for the past 25 years. Now it's Pelosi. I'm sure that as 2020 approaches they'll find someone new to demonize and scare their base with.
If you want some proof of the continuing right-wing obsession with a defeated (and retired) politician, here's the link with the Fox reporter in her hometown:
http://thehill.com/homenews/media/371110-fox-news-host-searches-for-hillary-clinton-in-the-woods