1. Reach the limits. Don't ask for increase if you have not "stretched" them.
2. Most of the times, they will increase every month.
3. To have better chances make big limits expands, a.) call them dont chat, b.) Be good seller(no cases, good listings, tracking numbers, no defects etc), c.) Tell them you plan to subscribe for a store. Once you asked about the items, quantities and their prices, say you are going to sell many and not cheap items. When they ask your suppliers, don't mention Amazon or retail marketplaces. I was mentioning mostly Chinese companies and local warehouses in general, "at this time being": Try not to lie directly, just hide some truths.