Bringing entrepreneurs advice and guidance from 30+ years' experience as an entrepreneur, small business turnaround specialist, investment banker, angel investor, business coach/mentor and author of "Secrets to Entrepreneurial Success"
Your situation is one that many businesses face. Stalled growth or down revenue is usually just the symptom. Could be any of a number of things, but usually is founded trying to use yesterday's solutions to address today's problems. Company's get fat, dumb and happy, just like people. In order to grow, you need to change. Here is a link to a blog post that should give you some insights and maybe set off a couple of light bulbs - http://bit.ly/1tvMFh9. Invariably, you need objective, outside advice to help really assess the situation. Happy to start a dialogue, if that makes sense.
All the best,
Less than a formal business plan, you need what I term a "battle plan," that is high level vision,direction and set of objectives with strategies/tactics and milestones to meet them. This is more project-like and your focus of launching, learning and adapting is absolutely correct. And as you do, you modify your "battle plan" according to "battlefield conditions" but always with your eye on your high level targets.
This should be a necessary part of your due diligence prior to completing your investment. Who else has invested, how much has been invested over what period of time? You should see a cap table and know what investment instruments have been used for prior investments (equity, either common or preferred; convertible debt/terms; debt/terms) before you invest, but if you already have, you should be able to get this information. My best advice? Ask!
It hard to give you solid advice on just the informaiton provided, but,clearly, something triggered this request and it appears fundamental trust might be at the root of it. If he/she has been an investor for a period of time, how well have you kept them informed about the business' progress? Have you sent out periodic financial statements? Have you engaged in periodic review meetings or dialogues with this investor (or the other for that matter)? If this is a new investment (with the last 90 days or so), have you executed an agreement with them? Were there any stipulations in that regarding the frequency or depth of reporting to shareholders? And, finally, (and this is my guess) is this investor one who has never done this before - i.e., put his/her money at risk? That may be the issue. Hope this helps you sort it out.