Auto-renew for Correspondence Chess

We need an automatic renew option for correspondence chess.  Meaning:  I like to play Bob ten simultaneous games.  When one ends, I'd like an automatic new one to keep the game count with him at ten.  

As it is, either we both forget, or we both remember, or he does it 8 times in a row, then I just never do, after all, he takes care of it...

then five months later I wonder what happened to Bob?

I used to play him all the time, but now, come to think of it, we haven't played in months.  

What happens is if you both challenge, then it gets out of control.  Ever game you end you both challenge and then instead of 10 games with Bob, you've got 25 and that's just too much Bob.  

Or I leave it to Bob and he takes care of the job until one day he starts to think I don't really want to play with him, perhaps I look at him and his low rating as a charity case, but it just drops off to nothing, as Bob was silently offended that I never took the trouble to challenge him back. 

It'd be nice if we could just set it at 10 games, or x # of games and done. not too much Bob, not too little Bob, just right amount of Bob. 

Of course, you have to both agree, and you could silently opt out.  But if you both could just set it at x number of games, great, no fuss, no wondering if you've been Black too many times... it's all taken care of.