Jane told us that her powers allow her to revive a person ONCE, as a Maid of Life, hence why Vriska had her as a support and out of combat, and Jane had previously used those powers on herself to revive her dream self. How is she able to just use them constantly with no limit now?
Because she doesn't have to worry about her revival limit if she's technically not DEAD yet. She's not constantly reviving herself, she's just KEEPING herself alive. Even when it quite nearly only makes only cartoonish sense and the only way she can speak is magically, ignoring the fact of her lungs with sheer godhood (ignoring any need for breath or blood with sheer Life Energy), which is just hilarious and I'm all for it.
Jane's actions throughout this final conflict and here have also shown the true scale of power a God-Tier player can tap into that the players weren't experienced enough to try or figure out back in their youth, which really makes her FEEL like a Goddess, and I greatly appreciate that.