An artificial kidney that regenerates dialysate includes: a catheter having an inflow lumen and an outflow lumen for communication with a peritoneal cavity of a patient; a fluid circuit in fluid communication with the catheter for circulating dialysate into, through and out of the peritoneal cavity; a pump configured to circulate the dialysate; a cleaning cartridge coupled to the fluid circuit for removing solutes from the dialysate, including a therapeutically effective amount of urea from the dialysate as the dialysate circulates along the fluid circuit; and wherein the fluid circuit is configured to receive a volume of ultrafilterate removed from the patient, such that the pump can mix the ultrafiltrate volume with the dialysate to an increase an overall therapy fluid volume.