Why does Passover HAVE to be Zionist? It's not as if the only way to say "Next Year in Jerusalem" is to say "Next Year in the Entrenched Likudnik Status Quo".
If you want to relegitimize Zionism, start changing it- ditch the "everybody else wants us dead" propaganda, ditch the assumption that neither Palestinians or Arabs can ever be trusted to live as anything other than bigoted berserkers, admit that Palestinians have legitimate grievances about what was done to them in the process of creating Israel, and admit that it's not reasonable to expect people to support the oppression of one community to prove the oppose the oppression of another.
None of that is that much to ask.
Also- and I ask this as a Gentile- why should Passover have to be Zionist when most of the Diaspora wasn't Zionist for milennia- when most of them saw "Next Year in Jerusalem" as simply a fond wish to return, probably for a visit or to return to live as equals with those around them, not as what has now become a permanently right-wing nationalist movement grounded in the worst 19th century assumptions of what nationalism has to mean.