I'm not sure how good this advice is, but I bought one of these on Amazon recently to clean off my brushes and I've noticed they've been lasting much longer as a result.
https://www.amazon.com/MyLifeUNIT-Artist-Brush-Multifunction-Holder/dp/B01HBL96LO/ref=sr_1_6?ie=UTF8&qid=1540388960&sr=8-6&keywords=master%27s+brush+cleaner