Focus is very important, but so is relaxation. Try to relax because I have heard that those who fear it won't return make themselves very tense by trying to force it. I call Reiki every day. It is important to stay in touch with the universal source.
Upon saying Reiki, it tingles my palms. It took awhile to get to that point. I rarely do Reiki symbols with my hands now. Mostly I use visualization of the symbols.
Once attuned, you have it forever as long as you do it for the greater good. So try eating nourishing food, relax with music and meditation, and go back to the beginning lessons where you learned to call Reiki. Do the simple basic steps, and Reiki will return. Talk to it. Tell it how grateful you are for this gift to mankind. Good Luck! :)
~Let us Scatter the Seeds of Kindness
and May Love and Light Always Find You~