Over time, soluble salts accumulate in the potting mix of indoor plants. These salts come from fertilisers and chemicals in tap water, and cannot leach out as they would in your garden bed, so need to be periodically flushed out of your pot plant.
If the leaf tips are turning brown for no apparent reason, then a build up a soluble salts may well be the culprit.
How to flush out the soluble salts in your pot plant
On a warm day take the pot plant outside (or if not possible, to a large sink). Using clean lukewarm or tepid water slowly pour water into the pot until it starts seeping out the drainage holes. Leave until water stops draining. Repeat twice. Empty all water from saucer or slip pot and return inside.