If I strain the liquid after usage, can I prolong the useful life of Metal Rescue?

Yes. The rust particles from the part are actually absorbed into the liquid, hence, the change of color from clear to black. Typically, there will be only a small percentage of rust particles on the bottom of the tub itself compared to the amount of rust removed from the object(s). Removing/filtering loose rust from Metal Rescue before reuse or storage will prevent the active ingredient in Metal Rescue from being exhausted. This will not reactivate the used Metal Rescue but instead preserve the corrosion removal properties.