Ongoing search engine optimisation - getting "link juice"
The creation of links to the website is vital to a sustained improvement in qualified traffic to your website. This must be accomplished over time (adding of links to the website in external websites, blogs etc.). Google will downgrade significantly any website which has many links added at the same time or even at the same time of day. The addition of back links is 'supposed' to be done by visitors to the website and so this needs to happen continually and irregularly (even at weekends).
Monitoring to evaluate and react quickly to any fall in traffic due to reduction in ranking by search engines.
Manual resubmitting to search engines of pages which may have been dropped by the search engines and submitting of other lower level pages. Search engines do not index all pages at once but need manipulating over time and continuously to link as many pages as possible.