70mb...you are awful close.
When you export, look at your 'images' folder and your 'media' folder. What is the size of each? If most of it is images, there probably isn't much you can do short of shrinking sprites, dropping frames, reducing color depth, and all that unpleasantness.
OTOH, if you have 20 or 30mb's of data under the 'media' folder, and most of it is SFX and music, you might have some options. If you are 'encoding' those files at more than 128kbps, I'd suggest shrinking them. 128kbps aac/ogg sounds far better than 128kbps mp3, and will only fall short in quiet environs with good headphones or excellent speakers.
volkiller730 is very right about checking your spritesheets; sometimes shrinking an object by 1% is enough to halve the resolution of the exported sheet. Still, that probably won't affect export size much (blank space squeezes down to nothing with png), but it can improve your performance and slash your memory usage.
Semi-Off Topic: Always work in higher rez than you'll end up using (at least 4x; preferably 8x) so you can go back later and 'reshrink' your graphics with minimal artifacts.