You should be able to enable developer mode and change the dpi-setting there. It is set at something like 436 (I think) originally, I have it set at 550 now (which is the largest setting that allows Agenda to work at all, and I still have full "tablet" "interface" working on a few other apps). This of course affects the size of ALL displayed items, so you will probably need to adjust the font size up as well. And all icons gets smaller as well, which I think is an advantage, because you can fit more on each homescreen. A few apps get problems with custom dpi-settings, but you will have to test that for yourself. I don't have any real problems with my apps and the 550-setting. Other than that, I am not aware of any way to change the size of the icons for just a specific app, unless that app itself has some kind of setting for it.