The optimal control of systems with gradual and sudden failures includes the evaluation problem of some stochastic parameters such as the failure probability, the average time before failure, the average cycle length etc. Some parameters may be calculated analytically if the degradation process is Markovian. But a problem arises for a non-Markov process. To this end, in more general cases we need to use simulation. If the failure within a regeneration cycle is a rare event then the regenerative version of Splitting method can be applied. We propose the Splitting method modification for estimation of degradation process characteristics. The point estimators are built by simulation of regenerative cycles.