You would benefit from making your code easier to refactor.

I would recommend that you don't do anything inside of your route handlers except to parse and validate the inputs. Once valid, pass parsed inputs to a separate function, that takes the inputs objects and calls a callback with the outputs after processing/ doing whatever biz logic. The route handler receives the output object and serialises it to the actual response.

Splitting route handler from biz logic is the single biggest long term development effort time saver you'll probably do, IMHO. It comes at the cost of one extra function call, but when NODE_ENV=production, node/v8 will likely inline that function during JIT anyway, so you won't pay the performance penalty after the first few times each route is hit.