what's happening here? a joke about Akagi line that said she don't know about Reppu?
I'm not familiar enough with KanColle (Never played it), but could it be regarding the cost of resources to create the planes, or just implying Akagi ate lots of Bauxite as usual?
It's because the Reppu (a very valuable equipment) was developed after Akagi sank, so she doesn't know about it. She's saying that it's a snack as a reference to how much she likes to eat and how you're able to scrap and convert equipment into resources in the game. Obviously since the Reppu is so valuable, you wouldn't do that, hence Kaga and the Admiral's anger at Akagi.
Updated
Why you…Trick-or-Eh.Oh,myReppuReppu?Leave it behind!Akagi-san?No...Yes, you do!!Never heard of it...Ah, could it be that you're talking about this?Akagi-kaiReppuuEven if you say so…You're mistaken here, it's just a new variety of snac-Kaga-san, there’s a really good reason for this…What's this I hear...You’re stacked full of it!Please say all your excuses in the commander’s office