my cat had kidney stone removal surgery but urniates very less

my male persian cat 2 years was having trouble to urinate.When i took him to the vet he did his X-ray and he diagnosed obstriction in the urinary system . He removed the blockage by a light or maybe someting like laser. when i got him home he was again having the same problem. After a week i took him again they found kideny stones . My cat then had his kidney stones removed . he was alright very much better than before he was urinating normally. but after 2 weeks (maybe not sure) he again had the same problem the vet said every thing is normal he then changed his food .He changed to some food which maintained the urniary system .After having that food my cat got very much better. But after some time his urine amount got less he licks his genital area very often. But apart from this problem i see no weight loss no appetite loss he is normal he is active his stool is even normal no blood in urine no problem during urine he plays he is good but the amount of urine has decreased than before just can't understand anything . If anyone there can help me out i would definitely appreciate.

If urine is decrease and he is licking more than usual, I would say it's time for another Vet visit

thank you for your advice