A year ago, I bought a bunch of indicating silica gel packets to keep my camera gear dry. Indicating desiccant is chemically treated so that it changes color as it absorbs water, letting you know that it needs to be replaced soon. But since silica gel is just porous sand, you can dry them out and reuse it again.
The outer fabric of my packet is made of Tyvek, which is designed to withstand up to 80°C without deformation. So I threw my packets in the oven at 60°C and checked the color every hour. It took around four hours for me to dry it out.