Okay, lets do it step by step.
First, if it's a product website, create a separate feed for products and submit the sitemap with Google.
if not, that may you would have separate news/articles/videos sections, create separate xml sitemap for each section and submit with Google
If not, make sure to have only search engine friendly URLs, who says rewriting 200,000+ pages is costly, compare this cost with the business you'll loose when all your products would be listed in Google. So, make sure to rewrite all the dynamic URLs, if you feel that Google might face problem in crawling your website's URLs
Second, study webmaster tool's data very carefully for warnings, errors, so that you can figure out the issues which Google might have been facing while visits your websites.
Avoid duplicate entries of products, generally we don't pay attention to these things, and show same products on different pages in different categories. Google will filter all those duplicate pages, and can even penalize your website because of the duplicate content issue.
Third, keep promoting, but avoid grey/black hat techniques, there is no shortcut to the success. you'll have to spend time and money.