There are two parts to the sensor - one is the I2C interface and the other is the ranging engine.
Writing a '1' to the soft reset will reboot the ranging engine - but you should not need to do that.
The Xshut pin will indeed shutdown the entire sensor. But unless you want to hold it in reset for some reason - like changing the I2C address of a different sensor - you should not need to do that either.
Simplest way to operate is simply to tell the sensor to stop ranging. The ranging engine will stop. The I2C interface will still be running, and you can issue the restart at any time. It will take off from where you were. All settings intact.
It does consume some power while stopped as we are keeping the memory and the I2C alive. But it's really minor.