What are the things to consider before changing the food & beverage menu of an outlet?

Well since you mention change, this means that the outlet is already operational so a thorough menu engineering needs to be made on the offering. There will be items that are stars, so you should keep them for the next menu as well. Than there will be some "plow-horses" present, which means items that are low on profitability but high in popularity, try to keep them but with an increased price. I would suggest you remove the dogs and puzzles since you are already considering a change.

So currently you have a core for the new menu, explore in which area are your shortages e.g main courses, desserts, starters and in which categories e.g chicken, lamb, vegetables etc. Consider your supply chain and the seasonal availability and add or remove relevant ingredients. An example would be dragon fruit, it makes for a wonderful fruit platter but i doubt it will be available in a reasonable price outside of Asia. So far you have created a series of factors that in combination will allow you in consultation with your chef to create some suggestions for the new menu.

Cost asses the new proposal, see what is fitting within your budget and what is not. It would be wonderful to have a salmon sashimi, but in a fine dining with an Asian or Japanese concept and not in a Mediterranean casual restaurant.

Having take all this in consideration create a recipe bank and start doing tastings, this will allow for a practical approach to test how labor intensive is the recipe and if it will stand in high peak or not. In addition, it will allow for input on the plating of the dish.Last, but not least call your most loyal customers, part of your staff, a server might identify an issue with a menu item, much faster than a chef or a Food & Beverage Manager, since he has boots on the ground.Hoped i helped and wish all the best

While developing a new or existing menu, one should keep track of seasonal availabilities of produce, cost of items, preparation time, cooking time, kitchen functionality in respect to menu itmes, staff knowledge and experince as well as capacity. Also take into consideration local tastes while maintaining the integrety of the concept of that outlet such as keep serving asian food in an asian outlet.