As the Goddess said, there was only one way to heal a curse that no healing or light magic in the world could cure. To make the future Saintess wish from the Goddess to take away this curse from him.
Yet, to be honest, Jiang Li actually did not care much if his life had a deadline.
His plan was not to butter Su Luxi up or make her feel coerced to wish for his recovery. If he could not stay long in this world, then that would really be a pity, but moving on should be easy since his goal was only to save a stupid girl and then he could go to the next world.
The problem might have been the fact that a certain someone did not know of it, so she pestered Jiang Li by repeatedly saying, 'Hey, there are only a few days left before the summoning, shouldn't you prepare plans to make the new girl like you or feel like she should use her wish on you?'