@BarryG: I thought from the verbage that she meant add memory, because as you allude to, increasing swap doesn't make much sense.
@equitana: If you really want to do this, keep in mind that changing the partition sizes in Astaro is completely unsupported, so you will be doing this at your own risk. If it breaks your install, you will have no option but to re-install from ISO, so save a config-backup to your PC before you do this. Use a LiveCD version of a partition editor, like GParted (http://gparted.sourceforge.net/livecd.php) to shrink another partition and grow the swap partition.