Joon Lee,
This is an outstanding question and I really like how you broke down the two areas that were most concerning because it shows you have put some thought into it.
- …Would you just keep pumping in more blogs and hope that you get more clicks?
What I would say to this is you never want to just be putting out posts unless they are something that is important to your readers/customers/clients. When people look at a magazine like “People” they know the magazine is about celebrities, etc. Yet, they buy it week after week because they do not know what is going to be written or about whom.
If online, the same tenets apply. If we are writing about SEO for example, sooner or later there will be another post about a given subject. But, if the writer is showing a different slant, a more relevant picture of the problem, etc. we still read it. Look on Moz for any number of topics and you see numerous posts on the same subjects, yet we still read them if they are relevant and present the data or information in a readable or unique way. Use point of view and layout, etc. to revitalize what you are writing and people will tell others of your posts.
2. As to similar “keyword themed pages,” etc. I would tell you to read what I wrote above first. If it is a page detailing a product or service, you can “update” the page as appropriate without creating a new page. (I would resubmit the sitemap or use Fetch as Google to ensure the new info is indexed quickly.)
But the real issue is how do I get traffic to my site after I have plateaued? That is where your creativity comes in. Do you have an email list that you regularly reach out to with pertinent info? If you are not doing that, it will help bring old visitors back. If you are selling something here is a phenomenal post by Codrut Turcanu on BuildFire.com. The post is more than about Local SEO so look through it. I found it on Linda Buquet’s blog. There are a ton of tips in there.
Yes, other ideas as posted here about long tail keywords, etc. do help, but in my opinion it is about keeping your reader engaged to the point that the reader recruits other visitors for you. I cannot tell you how many times I have suggested Moz.com to someone in the last 4 to 5 years. At least in the mid hundreds I would guess.
Good luck,
Robert