When studying the behaviour of dynamical systems, one particular goal is to find and isolate the periodic solutions and the equilibria. They are a subset of the chain-recurrent set of the dynamical system. In recent work, many improvements have been achieved in computing an approximation of a complete Lyapunov function of a given dynamical system and thus to identify the chain-recurrent set. A weak point in this approach, however, has been an over-estimation of the chain-recurrent set. In this work, we introduce a heuristic algorithm that reduces the overestimation in a simple and efficient way. Furthermore, a new and improved grid to evaluate the complete Lyapunov function is introduced to avoid unevaluated regions in the domain of the function.