1.Q: My site was listed on a search engine last week, but now it's gone. What happened?
A: Periodically, some search engines will purge outdated URL information, and occasionally an active site will inadvertently be removed. We recommend that you check weekly to verify your site is still in a search engine's database and to resubmit your site if it suddenly disappears from the search engine listing or starts to drop in the ratings.
Do not submit your site too frequently (more than once a day), because some search engines will consider this to be "spamming" and may delete your site from their listings. You also do not want to re-submit to a search engine if you already are ranked highly. Leave success alone.
2.Question:
How often do I need to submit my website to the Search Engines?
Answer:
There is no need to submit your website to the Search Engines more than one time. Once you are in their database of web pages, resubmitting your web page to the Search Engines again will not help rank your website higher.
The only time you need to resubmit your web page to the Search Engines is when you have edited your web page and changed your Title, Description, or general text you have on your web page.
Resubmitting is the only way to guarantee the Search Engines will notice the changes you made to your website the next time that their Search Engine Spider checks your web page for updates or changes it needs to take note of.
The best way to find out if you are listed in the Search Engines is to ask the Search Engines to search for ......
www.YourDomain.com ...... If they show your website in their list of results that means you are listed in their database and there is no need to resubmit your web page unless you have made changes to it and you want them to take note of those changes.
If the Search Engines do not suggest your website in their results, by asking them to search specifically for your own website Domain Name, that means you are not currently listed in their database and you need to resubmit your web page
I have more if you want.and note that spamming is for more than once in a day or 2 days not per weeks.
(i can give you the links on where i found these info if you want)