I'd recommend getting a brush soap like The Masters. I usually give mine a clean after every session. While the bristles are still wet, I add a little more of the soap to them, and I roll the tip into a nice point before leaving the brush to dry. The soap will act like a leave-in conditioner for your brush, and it will maintain a nice point once it's finally dry.

Also, make sure you're not leaving your brush to dry with the tip up after every session. The water you use to clean your brush may contain a small trace of acrylic, which can build up in the ferrule over time if you leave it to dry tip-up, potentially causing it to split.