This is a bit hacky, which always leaves a bad taste in my mouth, but I'm guessing that the slideshow needs a bit of time to make adjustments when the window resizes, so you need to let that occur first before you do anything that uses it. Try this...
$(window).resize(function() {
setTimeout(function() {
$('.subslide').css('top', $('.slides').height() + 132 + 'px');
}, 250);
});
It works when I run it on the linked page in the console.