This paper proposes the control of monomer concentration as a novel improvement of the kinetic Tile Assembly Model (kTAM) to reduce the error rate in DNA self-assembly. Tolerance to errors in this process is very important for manufacturing highly dense ICs; the proposed technique significantly decreases error rates (i.e. it increases error tolerance) by controlling the concentration of monomers. A stochastic analysis based on a new state model is presented. Error rates reductions of at least 10% are found by evaluating the proposed scheme comparing to a scheme with constant concentration. One of the significant advantages of the proposed scheme is that it doesn?t entail an overhead such as increase in size and a slow growth, while still achieving a significant reduction in error rate.