According to the latest promo on Nickelodeon UK & Ireland for brand new Supah Ninjas, the new episodes will begin to be shown from next Monday, January 7th 2013, at 4:00pm. The previously announced date, January 12th, in the previous promo was incorrect.
There are currently 10 episodes in Season 1 of Supah Ninjas that have not aired on Nick UK & Ireland. In January 2012, Nickelodeon UK & Ireland showed a new Supah Ninjas every Monday and Friday. If they repeat this, there will be eight episodes shown in January 2013. The remaining two episodes will premiere later in the year, along with the second season premiere.
Below is an online streaming video of the latest promo, containing the new info.