I've patched a crocheted afghan before and I agree with Jan. But you also might be able combine the two methods for less work and stress.
Examine the hole to see how many rows are broken vs. laddering. Begin to Frog a row or two from the bind off edge and swatch to match gauge/tension and measure the yarn needed for the task before cutting. This swatch is then Frogged to use as a patch for the hole.
A crochet hook of similar size to the needle used can be helpful with laddering without much need for patch yarn. A darning needle would be helpful with Russian joins to patch the broken row/strands. Or to use duplicate stitch to weave the patch into the edges of the hole.
You didn't mention the fiber type. So I guess I should mention that I work mostly with acrylic.
So now I think we need a topic thread on machine washings
Top Load vs. Front Load and the Gentile Cycle. How to avoid injury to your fiber friends.
Also remember Ben's adage: "A stitch in time saves nine!"
(hmm, I don't remember eating "Fruit Loops" this morning.)