The Path Less Travelled...

When you reach a certain level of development as an artist, you tend to unwittingly create a 'signature style' - that is, your art has a tone and character that is your 'style'.

Although this is a good thing, you still look for development and evolution as an artist.
To avoid 'going stale' or getting stuck in an artistic rut, the simplest method to expand yourself is to deviate from your style - use a different technique, different medium, aim for a completely different result. For example, the abstract artist could attempt a work in photo-realism, something completely removed from the work that they are known for - not to become a different kind of artist, but to bring a new layer of perspective to their creative process, perhaps something they had forgotten or hadn't considered previously.

It doesn't matter how far you progress in art, there is always something new to learn and apply in your specialty - like the layers of an onion, beyond the skill and technical training, there must come the insight, the foresight, and the engagement in vision and imagination of applying not only what is known but that which is unknown - each new element and HOW it is applied can bring a whole new dimension to the creative process, and once discovered and added to the signature style, can open new and different arenas for the artist to explore.

And it is in the exploration that the identity of the artist as an artist has an opportunity to evolve.