Both in color and in tenacity.
My great aunt knit this sweater for her brother/my grandfather (I think) and now my grandmother is wearing it. My aunt likes to put her in it because it is bright and cheerful (and Aunt Kay made it).
Frankly, it has worn like iron. It's acrylic. It was knit at a super tight gauge. The hem, cuff, and elbow are starting to show a little wear. But, otherwise, it was still good.
The first step was finding yarn to sub in. I didn't think I was going to be able to re-knit everything with yarn that I took out of the sweater. I started with the hem - I undid the knitting back to the point where it was stable and ran through a lifeline of waste yarn. I took a ball of yarn that was no longer attached to a big box craft store and looked for a match. I could not find a green that was the same. I ended up with a tweedy brown acrylic (Vanna's Choice, I think.)
Here's the fix that I did (and I did it pretty much the same way for the cuffs, except the cuffs were seamed together and the hem was knit in the round). First I picked up and knit from where he lifeline was using original sweater yarn that was still attached to the sweater. Once I completed the round (I started it someplace unobtrusive, like the side), I joined the brown yarn and continued to knit in the rib pattern until it seemed like enough. Then I cast off using Jeny's Surprisingly Stretch Bind Off. There was no good reason to have a tight bind off - my grandmother is living post-stroke in a nursing home and probably needs assistance getting dressed. Anything to make it a little easier. I was pleased that the bind off was just as stretchy as the rib.
Once the cuffs were done in a similar fashion - the hard part was doing this repair on the one cuff that was still in really good shape (It's hard to commit to taking apart good knitting) - I made an attempt to darn the elbow. I found good darning information at Martha Stewart and the Colette Patterns Blog (the Coletterie).
Here it is, ready to send back to the snowy winters of New York. Hopefully the repairs hold up half as well as the sweater itself has.