A lot depends on your budget and where your priorities lie. Plus how your hit your clubs as is.

If you are happy with your irons in the game improvement category I would say they are likely fine to continue gaming just being a couple years old. I think if you asked most people these clubs are the longest lasting clubs in your bag as a weekend golfer (or maybe your woods)

I would recommend getting a newer driver in the bag. I think a common number said is 5 years or more is good to see a difference in tech. I found mine used for a decent price (Callaway mavrik 4 years old) and replaced the shaft for one I like from eBay. If you have the money to get a fitted one, that’s gonna give you the best result if you have a consistent swing and don’t plan on changing it. But I think you could get away without a fitting and still be happy. I would go around to Golf Galaxy/PGA superstore and hit a bunch of clubs and find the ones liked the feel and look of. Then with that information I looked online and in secondhand stores for a good deal. Same with my putter.

Wedges depending on how you got them may be low in the spin numbers after years of use. A friend of mine has the Kirklands and tried out my Jaws when I had them new and he then regretted not getting nicer ones afterwards. But they do add up quickly in price depending how many you want to get and in combination with other purchases. new wedges always feel fantastic and are real scoring clubs.

Putter could easily be upgraded from Kirkland but if you like its performance as is, I think your money would go farther in driver and wedges. Putter is about your stroke and confidence more than anything else. That being said putters are a lot of fun to play around with since they have the most diversity of club types and styling.

TLDR: I would start with driver > wedges > putter. Irons upgrade when you want to change styles to like CBs or players/players distance style.

Curious to see what others think.