It may not be worth the effort to reform it, but claiming that it "can't" be reformed is asinine. A political party is not some higher order being, timeless and unchanging, nor even one with a fundamental permanent set of core tenants that all else springs from. It's a group of people with a bit of bureaucracy that influence and decide somewhat collectively on their shared goals. Of course that can change fundamentally.
In fact it has changed fundamentally in the not too distant past. Look at the Democratic party (and the Republican party) of the Jim Crow era compared to today. They essentially flipped to the other side of the political spectrum. It's absolutely not easy to change a party fundamentally and not quick to do so, either. Old minds are not easily swayed with the times. The primary way to change party ideals is through new minds and perspectives joining the party and the old ones leaving it. Generational change is slow AF but it does definitely happen. Concerted effort for young people with new ideals to join the party is the best way to induce this change. Again though, that is a lot of effort and takes times. The bigger he ship, the harder to steer. There are alternatives, all of which also take a ton of effort, probably a lot more effort really, but might be faster if it works out.