Propanolol blocks your somatic symptoms of anxiety, meaning your body's physical response. It does this by blocking epinephrine and norepinephrine. It blocks your "fight or flight" response, in a simple way of explaining it. It would be fine to go back on it under your Drs supervision. But it is not wise to go on and off it repeatedly. It is also not wise or useful to take it sporadically.
I hope this helps to answer your question.