So this weekend, I've planned to avoid. It's baseball season (yay!), so I have an excuse to not come to bed. I'm torn to whether or not she'll care, or if she does, if she says anything. I've rejected her in the past a minute amount of times, and she generally hasn't taken it well, but I've had legitimate excuses (total exhaustion, mainly). But I've never said no to, or avoided sex with her when I'm feeling fine.
It's juvenile, but it's also pretty last ditch. It's likely it won't help things, but I'm at the point now where I'm genuinely tired of simply doing it on her schedule. I also feel (well, know, really) that she obviously requires this schedule to become aroused and/or psyched up to have sex.
Instead of doing something that might make her feel rejected, tell her you really want to be with her but that due to baseball you would like to try and change up the routine that the two of you have become accustomed to. Ask her if she would be OK with a random time during the week instead and if the two of you can just try playing by ear to find a time.
This would at least not make her feel rejected, but confront her with your desire for the two of you to become more flexible and not become so routine. In my opinion the idea of making her feel rejected will only set you back and cause both of you pain, but sometimes that can be necessary in order to progress and change.