If insanity is defined as doing the same thing, over and over again, expecting a different result, then many triathletes can be defined as insane.
If you take a look at your training over the past years, has it changed? Have you seen clear and steady improvement? If not, then why are you still doing it? Are you expecting a different result from that weekly group ride you do, week after week, season after season?
Are you still pounding away at the water, lap after lap, same lane in your masters group? Have you seen faster swim splits?
Has training been consistent for the past year? What were the things which hurt consistency? Was motivation ever a factor?
Have you been battling injuries? Has there been a consistent theme to the injuries, such as overuse, crashes, or even too much, too soon?
If you're really looking for a break-out a season next year, it's time to honestly assess what you've been doing, and how to improve it. Can a coach help this? Absolutely, but it's not necessary. Just a simply review of your training log can tell you a lot. Don't have a training log you can review? There's a big sign right there, make changes which help you see a more clear picture of what you're doing as an athlete, both right and wrong.
It can be very challenging to honestly assess oneself. Many times we are so clouded in our perspectives, rightly or wrongly, that we miss some obvious things. Ask some training partners what weaknesses they see in your training and racing, and how they think you can address them. The answers might surprise you, especially if you ask a range of athletes, from those faster than you to those slower than you.
If what you've been doing hasn't worked, then stopped doing it. Change the focus of your training to more speed if you've been doing distance. Lose weight if you've ignored it. Change your masters group to a smaller, or bigger group, to try and get either pushed harder, or more personal attention.
In the end, if you don't accurately assess where you are right now, and how to make changes to improve things for next year, you're just going to have the same results.
Best of luck!