Adrian, I think that you could remove the old sripes and replace them. - or not. Your car is only 2-3 years old so I think there is a possibility. You never said how big the stripes are on the car.
Here's what I would suggest. First, check locally for someone who does vinyl stripes. If you cannot find them in the yellow pages, check some body shops and see who they use. If you find someone then ask them if they could take the stripes off for you.
If by some chance you were feeling brave I think that you could remove them yourself. A heat gun should soften them enough, (using care not to blister your paint the heat gun by using the low setting and just warming the stripe well but not melting it) would refresh the adhesive enough to make the stripe removable. If the heat gun scares you, then a blow dryer on high would definitely be safer. You can get a bit loose with a fingernail, then heat just as you pull. It will be a pain in the ass, but it should come off. If the stripe goes onto urethane bumpers and such, it may be a problem.
Once you got the vinyl off you could use good old fashioned lighter fluid on a coarse terry cloth towell to remove the adhesive. Of course DO NOT USE BOTH AT ONCE or it would catch fire and burn you and your car to the ground. The lighter fluid will not hurt your paint at all and is less expensive than goo-gone and that sort of thing. Sometimes if you can just get a little piece started, you can jst drip lighter fluid onto the underside of the peeled edge so that it contacts the adhesive and it will pull up. Slowly, and you have to find that balance of drip it on, let it soak a few seconds and then pull and repeat. It's a slow process but it works. Practice on labels you have on items in your home, the label on your cigarett lighter, the price tag on the bottom of that vase.. anything with a hard surface. Wal Mart has lighter fluid pretty cheap in larger containers.
Then follow up with a good wash, polish and wax.
If it were my car, I would take a shot. But then, it wouldn't be MY first rodeo.
Would love to see a photo or two of the stripes you are addressing.
Kate