I've actually not upgraded a lot of my plugins this year, even though I've bought more this year than any other.
I've found that some clients are so well educated they sometimes ask you to use particular plugins. Have others found this? Especially Waves plugins, the name is so widely known that clients equate them with a well setup studio. Kind of like Pro Tools being perceived as the essential DAW. Especially for the younger guys that have grown up with computers and not seen the high end audio gear. For them Waves equate to the high end studio hardware. I admit that years ago when I got into digital, I had perceptions like that. I guess you get sucked up in the marketing hype.
Like a wise man once said;
"Maybe it's time to cut down on the VSTs"