Hibernation is currently not working reliably with Ubuntu on the One.
In order to use hibernation the swap partition must be at least as large as the amount of memory you have. Ubuntu can now run with a swap file just as efficiently as a partition but you cannot hibernate to a file.
Resizing partitions in general is a dangerous process (unless you are using LVM). I would normally recommend reinstalling unless you have done a lot of customising that you cannot easily repeat.
However, there are tools available. gparted is a command line utility that will do this but I wouldn't recommend it unless you really know what you are doing. Ubuntu comes with Partition Editor, which should also work. There are also commercial tools like Partition Magic, which can resize ext2 partitions.
Whatever you do, don't attempt this unless you either have no data you care about on the machine or have backed it up.
In 3 days, a completely turned off laptop discharges by 6%