For changing the swap size you would need to first disable the swap:
swapoff (swap partition)
sudo dd if=/dev/zero of=(swap partition) bs=1M count=(newsize in MB) oflag=append conv=notrunc
mkswap (swap partition)
swapon (swap partition)
The point is that you have to always try to avoid the swap usage; usage that does not matter so much in the ammount of disk space; is true that if you have a bigger swap space, you can handle more processes, but the aim is to try to avoid the use of swap, as it will worse the general system performance.
Anyway, that does not mean that you have to disable it, it is always recommendable to have some disk space reserved for swaping for emergencies. The general recomendation is:
If RAM is more than 1 GB, swap size should be at least equal to the square root of the RAM size and at most double the size of RAM
So if it is possible try apply that rule, as long as you hard disk has enough space.