Repotting houseplants has multiple benefits, the major one being it gives them more space to grow. Otherwise, they can become congested and root-bound, making it difficult for them to absorb the nutrients and water they need.
As well as this, repotting allows the opportunity for new potting soil, which is rich in goodness and free of salt build-up from fertilizers. What's more, repotting your indoor plants gives you a chance to inspect their rootballs and remove any diseased or decaying areas. This is particularly useful if you've accidentally overwatered your plants and they're suffering from root rot as a result.
