Confidence votes 174. DNA has to replicate before mitosis to keep the number of chromosomes and DNA in the cell consistent. Mitosis is the process of reproducing cells by splitting one cell in half to make two. If the DNA didn't replicate, the two daughter cells wouldn't be able to have a complete strand.DNA replicates by dividing in half, then creating a mirror image of itself. Replication gives both strands of DNA an EXACT copy.itosis is the process of reproducing cells by splitting one cell in half to make two. If the DNA didn't replicate, the two daughter cells wouldn't be able to have a complete strand. DNA replicates by dividing in half, then creating a mirror image of itself.