I recently went to my local Trek (“flagship”) store with my supercaliber and asked if I can get an appointment for the shock service and was a bit shocked to be told that they cannot offer any shock service in their workshop, or in the two other shops they have in the city. They said they can offer me to service anything else but the shocks. 
Funny thing is they sell the supercaliber in their store which they apparently cannot service.
Oh well, so I went ahead bought me a seal replacement kit as well as oil for the rear shock and the tools for the replacement of the rubber seals, so I can do it myself. My bike has about 100h now, mostly good weather, so I think I don’t really need to replace the rubber seals yet. I would like to refresh the oil though. Can anyone tell me if I can clean and reuse the foam sponges inside? (It was kinda hard to get the seal kit where I live and I don’t think Trek sells the sponges separately).
Or is it not a good idea and I should go ahead and replace the rubber seals and the foam elements together?
What is your procedure for this? I think this is what I am looking to do?