Repeat Submissions to Search Engines
Those who tell you that you need to submit your site repeatedly are either mistaken, or trying to get you to buy their service.
It is not necessary to submit your site to the search engines more than once, and you really don't even need to do it once if you have other websites!
Search engines regularly re-spider the web. When they do, they follow the links on established sites, so if your site is linked into an existing site, it will get found and indexed, even if you do not submit it. Once it is found, it will be re-spidered every so often - if you make regular changes, it will get spidered more often, if you let it sit there for six months without any changes, it will get redone less often.
The only time you need to resubmit a site is if you change its domain, or if you neglected it, and then made a whole bunch of changes that you want to have indexed right away. Otherwise, forget resubmitting, it is a waste of your time, and in fact, may be seen as spamming by some search engines, which can hurt your site. In fact, many search engines tell you outright to not submit your site more than once unless there have been major changes (and then it is only necessary if it has been unchanged for a year or more).
Don't buy a service that promises to resubmit on a monthly basis. It is a waste of money, and totally unnecessary (and can reputedly get you banned). Just let the search engines do their job, and you get on with your job, which is providing good products or information!
Your time and effort can be better focused on creating new pages, adding new products, or otherwise making regular enhancements to your content. It is the most effective way to keep your site accurately indexed, AND the best way to attract good visitors!
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