A large number of hardware faults are being caused by an increasing number of manufacturing defects and physical interactions during operation. This poses major challenges for the design and testing of modem Multiprocessor System-on-Chips (MPSoCs). Intermittent faults constitute a major part of hardware faults and their fault rates can be used as an indicator of the wear-out in a Processing Element (PE). We propose a run-time task re-mapping method that uses this information to improve the useful lifetime of MPSoCs. We also propose a scenario-aware system-level fault injection technique for intermittent faults to evaluate system-level design techniques in MPSoCs. Our performance results conclusively show that our strategy significantly scales on reliability metrics with respect to number of PEs. Specifically, we show that our method can achieve an increase in lifetime of up to 16% and tolerate up to 30% more faults than state-of-the-art techniques.