The Lazarus Pit has to have a long-term effect on secondary genders in the Omegaverse, right? If Ra's was an alpha, what if after so many times being revived via the Pit, using it to maintain his youth, he doesn't have ruts anymore? Can barely smell anyone else's pheromones or produce his own? He can’t engage with his pack to the degree he wants to, or should, as a pack alpha. Yes, he loves his children and grandchildren dearly, but he "can't bond with them" because he can't scent them. He's functionally a beta, and feels that his position as a leader is slipping.
So he contrives a plot to have Respawn created, not as an organ donor, but as the body he'll take over once it reaches maturity. His daughter's intellect and beauty, Slade's strength and regenerative abilities; he shouldn't even need the Pit after this. So, theoretically, a flawless plan.
It's just that he's a very willful child, something Ra's doesn't necessarily discourage, it bodes well that his mind is so strong-- it's only an issue when Respawn manages to break his own wrists to escape during one of his periods of being left alone, slips into the upper levels of the base, and runs headfirst into Damian, recently presented omega.