Highly Skilled Migrants are allowed to change employers while their residence permit is till valid. The residence permit continues as long as you fulfil the conditions, even if you change employer or obtain another position.
If you no longer work for the employer or change your position, your employer must pass this information onto the IND. Have you found another job? Then you must inform the IND yourself of your new employer. You must do so within 4 weeks. The IND will then review whether the conditions are still being fulfilled.