A - When you are a senior associate at a law firm it is a real watershed moment in your career. At this point you should know what being a partner at your firm entails and whether it is something you want to do. Just as importantly you should know if your firm has earmarked you for partnership.
If you don't want to be a partner or the firm does not see you as a future partner you should - in most instances - always move on. You will find there will be other opportunities at other firms which are far better for your career. Other firms may have a different structure, a different work/life balance or different goals and priorities which may make them a far more attractive and likely option for partnership than your current firm.
Also, there are roles in the in-house market that may present better career options - though these roles can be very competitive and demand for these roles far outstrips supply. Most of all you need to make a decision; sitting tight can stall your career and reduce your future options significantly.