In general, I think the only part which is supposed to need regular replacing is the ablative heatshield. Regarding Earth vs Mars reentry, he said the following

In general, I think the only part which is supposed to need regular replacing is the ablative heatshield. Regarding Earth vs Mars reentry, he said the following during the talk (my quick transcription follows): "You're going in, you're going very quickly, 7.5 km/s. For Mars, there will be some ablation of the heat shield. So, it's just like a brake pad wearing away. It is a multi-use heatshield, but unlike for Earth operations it's coming in hot enough that you will see some wear of the heatshield."