All perfect praise be to Allah, the Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad, sallallahu ‘alayhi wa sallam, is His slave and Messenger.
If you wish to repeat Soorah Al-Ikhlaas or other Soorahs, you should repeat the Basmalah each time you start one. Ibn Al-Jazari wrote, "I could not find a text regarding the case when the last verse of a Soorah is recited and followed directly with the opening verse of the same Soorah, when repeating Soorah Al-Ikhlaas, for example, without a pause. The most likely correct view is that the Basmalah must be recited, because the Soorah is recited from the beginning." [An-Nashr]
Allah knows best.