This weed is hairy bittercress, a winter annual that germinates in the fall. It reproduces by seed. At this point, hand pulling or weeding with a tool before the seeds disperse is the best option. Lawns that are not dense or lawns are mowed too short or are in shade allow hairy bittercress to outcompete the lawn.
The crabgrass preventer will not control this weed now. A preemergent in late summer summer to early fall will prevent germination but you will not be able to sow grass seed if applied. See management options http://extension.umd.edu/hgic/topics/hairy-bittercress