I have cleaned my carpet twice and after a while, about a week, the stain reappears. It is really upsetting. The stains are from my puppy and so I use the steam cleaner but the stain reappers.

Answer: Sounds like you have a bad stain on your hands! When spots reappear, that’s a sign that the spot or stain has gone into the padding below. Here’s what you should do; pretreat the stain with an enzyme action based product such as Pet Stain & Odor Pre-treat for Carpet & Upholstery for 48 hours. Then give your stubborn stain one more go with your upright deep cleaner. 
To make sure you reach the padding of your carpet, run your deep cleaner back and forth over the spot until you no longer see color coming up from the clear nozzle on your deep cleaner. 
After deep cleaning, if spots happen to come back again, just touch it up with OxyPro® and let stand overnight.