Guidelines. It’s really hard to define useful guidelines about how often to change your strings, simply because there are so many different factors and each string will have a slightly different lifespan. On many internet forums you’ll find recommendations for changing strings ‘every 120 hours’ or ‘every 3 to 6 months’.sage. The amount of time you spend playing your violin will obviously affect the lifespan of the string! The more you play, the more the strings will vibrate, and the more their lifespan will decrease. However, there are things you can do to minimise the impact.