Answer: For more bloom, first ensure that the plant is growing vigorously. Typically in your area the soil and water are alkaline, and camellias prefer acidic soil. Miracid, which has an acidifying effect in soil, is the right approach. Also consider a product called Dispersol that is available in your area. It is a combination of iron and sulfur that is more acidifying the most fertilizers. Ask at your local nursery about "acidifying" fertilizers recommended for camellias.
Organic fertlizers such as cottonseed meal are also recommended for camellias, as is a 1 to 2 inch deep mulch of organic matter such as fir bark. Both of these materials will also gradually acidify soil.
Pruning camellias is generally beneficial. Remove crossing and overly crowded branches, always cutting back to another branch. Remove branches and twigs you don't want all the way to their base, not half way.
I am surprised that your plant has only bloomed once. There are many kinds of camellias and some bloom more often and more reliably than others. I suppose you might consider replacing it if these other attentions don't stimulate it to grow and bloom better.
For more background information, you might consider an article in National Gardening magazine about camellias some years ago. You can find it at:
It might answer some more questions for you.
I hope this information helps.
Q&A Library Searching Tips