If you can increase, then you should. If not, do it until you are able to support the weight.

Be informed that SL is about on the same level as starting strength, it's for beginners. If you have been lifting for a while, you would have gained enough benefit from these workouts hence the plateau (I am assuming you know what you are doing with nutrition here).

Look up wendlers, 5/3/1 or even madcow for intermediate lifts. If you think you're not up for it or would rather stay at beginner level and want some variety in your routine then by all means try SL.