Perhaps someone a little more vulnerable in general might be a good idea. I think I remember reading somewhere that she basically has that seat for life.
Indeed, unfortunately while I am quite disappointed in Sen. Feinstein, to lead a revolt against her would require finding someone from within SF progressive circles who is willing to vote similarly to her in so many other areas, and I can't imagine anyone with such juice - Barbara Boxer poses the same problem. Neither of them is likely to lose their seats anytime soon.
Fighting back isn't about getting what we want today, it's about being on a road for it. In your community, wherever you live, there are probably a handful of issues that overwhelmingly drive each election. This is true most places. It's important to make sure that Internet Freedom ranks alongisde things like Worker's rights, Women's rights, Immigration Reform, etc..
It's important that the next generation of politicians have no choice but to address this as part of their platform.
While I really like the fiery call to action another commenter made about "nailing their scalp to the wall" with anyone who supports this, it's very clearly a generational problem. I think a lot of damage could be done to unseat someone like Feinstein or Boxer who do good jobs of standing up for other issues and are simply ignorant on this one, and probably always will be. Hopefully they will staff up, listen to the EFF and ACLU, and I can tell you from having been involved in activism from the jail cell to the armchair that when you call your representative you are helping to DEMAND that they meet with the experts who are on our side. When we choose a day to call them, that means that everyone in congress will be talking about this issue today, whether they like it or not, even if every time their chief of staff speaks to them they mention, "and lots more people called about the internet."
This tells them that a bunch of people are upset, and even if they can't or won't each individually give us exactly what we want - votes for and against, depending on the situation, it registers that to preserve their career they need to engage this concern somehow.
Generationally, we will win this. We will undo whatever damage the current generation of power brokers do, but undoing fucked up legislation is REALLY FUCKING HARD, so if we can even round some of the corners for the discussion we'll be having in ten years, if we can even slow each lost battle by a year, by a term, by a decade, the tide will turn, some of today's ignorant voters and legislators will die, and we will inherit a world that has far more flaws than flawed internet regulations, like dying oceans.
Also I wouldn't be too hard on the OP, activism is hard, and it's fucking frustrating, and it sounds like he or she engages with a lot of activists and doesn't hear the greater conversation they're trying to influence, but hears the DEAFENING BLAH FUCKING BLAH which I totally sympathize with, but that DEAFENING BLAH FUCKING BLAH is a whimper to some people and sometimes we just need to mostly agree on a message and execute it and come back tomorrow to do it some more.
If the alternative is shutting up and watching the wrong shit happen and complaining next week that noone wants to help with my awesome activism plan, I'll be calling my representative today.