And, indeed, this may be the appropriate remedy. However, a different approach might be equally effective, or even more so to get that elusive zip back into your racing. Maybe instead of ramping up your volume you should cut it back. Significantly.
Seasoned endurance athletes have so many years of so many miles stored up in their neuromuscular systems. This is why we can bounce back after a layoff (when we are "so" out of shape) and get back to top form very quickly. However, that top level of fitness can also be a rut in the road, wagon wheel tracks that are six inches deep because year after year we achieve that certain level of fitness but never surpass it. So, while all those years of training are a big help when it comes time to get back in the swing of things, it can also be a hindrance to our progress.
Let's say as a runner you are accustomed to 60-mile weeks. You do some sort of speedwork once/week and a weekly long run on Saturdays. You run 6 days a week. What if instead you cut back to 40 miles per week? You shortened your speedwork intervals from 800s/1000s/1600s down to 400s, completed your long run every other Saturday and incorporated more recovery days during the week (either days off or shorter/easier runs). Your fear would be, "I'm going to get out of shape." It would be mine, too. But, time and again, I see my athletes benefit from reduced volume and better focus on (1) their workouts; and (2) rest and recovery. The added rest and lower volume adds much needed "snap" to the legs, allowing athletes to train and race at a higher level. Those wagon wheel ruts would fill right up and you'd be charging down a new path of less resistance.
As a real world example, one of my Masters athletes was concentrating more on running (than swimming or biking) this past fall/winter. Just to try something different. She swam/biked 3 days each per week and was running 5 days (about 50 miles). Now that Summer is approaching, I added one day per week on the bike and cut back to 4 days per week running. During only the second week of this new approach, her running took a big step forward in speed.
She is not training any harder or longer. All I did was change things up ever so slightly - changing one run workout to a bike workout. The effect on me was noticeable and significant. Because she is not pounding her legs as much (running trashes the legs more than biking or swimming), they are more fresh day in/day out. This allows her to push harder within a given HR zone (non-recovery) and, thus, get more out of the workouts. The higher volume running weeks laid a nice foundation but also dug deep wagon wheel tracks. Now she has broken out of them and is moving forward faster than before.
Come Summer, I'll be cutting back her running to 3 days a week. By then, she won't have to worry about losing any run fitness. And the added zip to her step will allow her to race strong and hard, without worry of fading away at the end.
If you're feeling the need to try something different, try decreasing your volume. If you don't realize the results you are hoping for, not to worry. You can ramp things back up and be no worse for the wear. On the other hand, decreasing your volume just might be the shot in the arm your training routine needs.