Help bow with his operation

Hi, my name is Heidi and my cat Bow is 4 years old. He is a small brown and black domestic short hair that was rescued from an abandon warehouse as a kitten. He has been diagnosed with urinary crystals and has know gone through one procedure to unblock his urethra. Within 24 hrs he has blocked again. I am unable to afford another procedure and am requesting assistance to help my young cat at his second life.