After a year or so in the same pot, it might be time to give your plant a change of scenery. After about this long the plant will have sucked all available nutrients from the soil and will reach a plateau in terms of growing - if it has no more food to eat, all you're doing is maintaining it by watering it. 

If you really want the plant to grow, you need to repot it with a fresh potting mix. If your plant has been in the same pot for more than a year, you can go up a size. However, don't go bigger than an additional inch in diameter. Giving the roots too much extra space in one go will overwhelm them. Too much soil relative to the size of the plant means that the soil will retain a lot of moisture. If the roots are wet for too long it could lead to root rot, which is not good for the plant. 

After picking your new pot, it's time to prepare the new potting mix. Ask at your local nursery for the best indoor potting mix for your type of plant. Different plants will have different nutritional requirements. For example, succulents need a mix that has a high quantity of sand. For extra measure, add a dose of seasol in with the mix. Add a layer of the mix to the bottom of the new pot, about 1/3 of the way full. This will be the bed for your plant. 

Now you're ready to remove the plant from it's old pot. Grab the plant at the stem or stalk as close as possible to the top of the soil. Hold on firmly and give it a bit of a jiggle to start loosening it up. If it's in a plastic pot it helps to squeeze the bottom. Once you start to feel some give, start to slowly raise the plant up. 

Once it's all out, give the roots a slight massage to get rid of any old, dry dirt that's still hanging on. You can then place the plant into the new pot. Fill up the edges around it with the rest of the potting mix and make sure that it's snug - if it's a particularly heavy or large plant, you don't want it drooping later. 

Your plant will be a bit taken aback for a few days - a major change like repotting can be quite stressful on it. Make sure to give it a good dose of water and keep an eye on it for the next couple of weeks to see if it needs anything else. 

Repeat will all other plants that need it as often as necessary. Happy gardening!