The answer to this question was already provided to you if you remember. If you do not remember, yes, you can actually use briquettes more than once. But, there are a few key factors that you should keep in mind when doing so. For starters, if you do plan to reuse your briquettes, they need to remain dry. Because of this, always ensure that you are covering your grill when you are finished using it (allowing the surface to cool down a bit beforehand). This way, no rainwater can get inside and ruin the briquettes.
Yet, it also may be wise to use some fresh coal with the coal that is already inside. Outside of the fact that there is probably not enough in there, to begin with, this still allows some fresh charcoal to be used.