What I can propose is to use JavaScript - set "onLoad" in your right frame source which will refresh left frame each time right frame is refreched. But it is not really good for a normal work: you select smth in the left frame --> you reload right frame --> right frame reloads your left frame. But if it suits you, it is a way.
May be, there are some other events in JavaScript which you can use, something like "onRefresh", I don't know. Check it first if you'll decide to do it this way - may be, some of them act only on "refresh", not on "load", and you will have no problem with refreshing left frame each time you change right one. But I have a big doubt such events exist. I don't know one, at least :-)
