That mix didn't provide any fertilizers or food that gets depleted, and it hasn't been months or years that you're using it over and over again, so I see no problem with reusing it.

I've been wondering the same thing, but recently (yesterday) decided not to reuse it.

Fresh, clean, propagation mix seems the right way to go. And in the establishments in which I have worked, it was never re-used.

At the end of the day after tubing the rooted cuttings, we would tip our propagation mix onto a miniature mountain range. This mountain range has been about 20 years in the making. I don't know where the mix went that we used in my previous place.

Thanks for the input. I am coming to the same conclusion. I figure if I can increase my success rate by 10 or even 15% by using a clean propagation media, it would be worth the extra investment. I could always deposit my used growing media into my raised beds. It would do nothing but good there.

I found an article that said the following:

Peroxide Mixture

Hydrogen
peroxide comes in different strengths, but the 3-percent solution commonly sold
at drug stores is the most suitable choice for perlite sterilization. Dilute
the peroxide further by mixing 1
tablespoon per quart of water; otherwise, the solution
is too strong and may damage or kill any plants grown in the perlite. Mix up a
fresh batch of solution each time you need it or keep extra solution in a
sealed, labeled container so evaporation doesn't alter the dilution of the peroxide.

Application Method

Watering
the perlite or perlite and soil mixture with the peroxide solution before you
plant usually provides sufficient sterilization to prevent fungal and disease
problems. If fungal growth is an ongoing problem after planting, you can
continue to water once every week or two with the diluted peroxide. If fungal
growth appears immediately after you sow seeds, fill a spray bottle with the
solution and mist the soil surface before the seeds germinate. This destroys
any fungal spores introduced during sowing.