The Daleks are a race of robot individuals with subtly distinct personalities, and as such, they do not belong to a hive/collective mind. They are not biological and cannot be born, so how do they reproduce and how are new individuals introduced?
A Dalek is a metal armour encasing a Kaled mutant (a "Muto"). This is the one-eyed octopus-looking thing you see in many Doctor Who episodes where the Dalek's armour opens. A Dalek itself will not reproduce, as once the Kaled mutant has bonded with the armour opening the armour generally results in death.
Mutos are of descendants of those mutated by chemical weapons in a war between Kaleds and Thals, both residents of Skaro, so they must be able to reproduce in some form. This isn't revealed (understandably, in a children's program) but given octopi are also able to reproduce the mental image I'm getting is something similar (apologies for anyone else with a vivid imagination).
Apart from that, Daleks are known to use cloning to reproduce (as seen with the new "Paradigm Daleks") and have also shown a propensity to try to mutate humans and create new Daleks with these mutations, as Kaleds originally were similar to humans in their physiology. The army established by the Dalek Emperor before being destroyed by Rose was born of Daleks formed from mutated human DNA.