Working with cycles in meditation
I was wondering about the clearing away of the shrine. It could be that there exists an attachment to the shrine. By clearing it away when periods of stagnation occurs it is like affirming that a period of stagnation is "bad" or "not good" or "a problem".

These are merely concepts designated to a certain situation. In ultimate reality what you experience is only a combination of hearing, seeing, tasting, smelling, feeling, thinking.

Making the situation into either positive or negative is one's own work. We create our own suffering by wishing for reality to be something different than it already is. 

The clearing away of the shrine could indicate that there is a self involved in this. It is like saying "i am angry" or "i am sad". There is an affirmation or validation going on here. 

In reality there is mental and physical phenomena arising and ceasing on their own accord. Do not identify or take ownership of these impersonal and uncontrollable phenomena.

By reacting to them you provide them further fuel to burn. See them for what they are. You can turn these phenomena into objects of observation and create a foundation for cultivation of insights.

Lastly, here is a great dhamma talk by Ven. Yuttadhammo. Robin was so sweet to post it in one of my questions. In here it is talked about how one can adjust ones own practice by using 4 different tools. This talk is very beneficial for any meditator. 

Hope this helps. If you need me to elaborate on anything i've just said, please let me know.