The tool 'ubuntu-device-flash' can be used to update the software on an ubuntu phone manually. It can be used to change the device to a different 'channel' of updates and also perform a reset of the storage.
However, when I tried it with either the BQ Aquaris E4.5 Ubuntu Edition or Aquaris E5 Ubuntu Edition, it didn't seem to work, for example:
ubuntu-device-flash touch --channel ubuntu-touch/stable/bq-aquaris.en --bootstrap
Would be expected to wipe the device to factory state. However, it does not seem to succeed:
2015/03/27 13:58:35 Expecting the device to be in the bootloader... waiting 2015/03/27 13:58:50 Device is |krillin| 2015/03/27 13:58:50 Flashing version 20 from ubuntu-touch/stable/bq-aquaris.en channel and server https://system-image.ubuntu.com to device krillin Failed to enter Recovery