It's good to see you again! And oh my goodness, Laci is too cute for words!
I also have an extremely picky, extremely stubborn, eater (who now has late stage CKD so is even more difficult to please), so I commiserate. Celia would rather starve than eat something she doesn't want to eat - which is actually where we have been for the past couple of days. I have opened 6 cans of food in that time.
How old is Laci? It's possible that there's something medical going on, so just in case, I'd probably want to have her checked out. The first thing that I would wonder, especially since you mention the messy eating, is whether she's got an ouchy tooth or something else going on in her mouth.
If it is just fussy eating, what I've discovered seems to work best lately is to never feed the same thing more than two days in a row, and to introduce a new flavor regularly. That keeps her interested. Most often, Celia will eat about 1/2-1/3 of a 3-oz can for her first two plates but won't eat a third, so I switch to a different food for the second two plates (being a kidney kitty, she gets fed very often). If I'm lucky, I can use the rest of at least one of the cans the next day. Even storing the leftovers in glass containers, she sometimes won't eat them the next day, and certainly not after 2 days. The big cans are a total waste, as she'll rarely eat more than 1/3.
Or is it a texture issue? Is there a certain texture she prefers? Celia will only do pate. Chunks I can put in the processor, and some come out smooth. Shreds she won't do at all - just licks the liquid - and they don't smush in the processor.
For extra calories, you might try kitten food every few days, or go with higher-calorie foods. Weruva, BFF, and foods in gravies in general seem to have fewer calories than pates. If you're not familiar with these lists of canned foods, they both give calorie totals of a bunch of different brands. Tanya's: Tanya's Comprehensive Guide to Feline Chronic Kidney Disease- Canned Food Data USA
. This one is arranged by lowest phosphorus, just fyi, but the calorie count is there.
The other is from catinfo.org. When I tried to copy the link, it persists in wanting to download the pdf, but you'll see it from the home page.
Hope you get her eating!