asp.net page content updated delayed

It's not clear from your description what the association is between the web site and the database, but I'm going to guess content for the web site is stored in the database. When the database is changed, you expect the web site to change as well.  I see two possible answers for the problem you're seeing:

1) The web site is pulling from a database other than the one you update.  In other words, you update a database and that database synchronizes with a live database once a day.
...or...
2) The web site pulls from the live database server all the time, but some product is caching the web site and showing you the cached pages.  The caching could be at the web server itself, the web browser you're using, or some appliance (web proxy) in the middle.

I think you'd know for sure about the first scenario, but maybe not.  

In the second scenario, I'd think you'd know if you were using a proxy, but maybe not.  You can test the browser caching idea by switching browsers or switching machines to see if the new page shows up.  IIS has cache settings at the site level that can be modified, either in web.config or through the ISM.  It's also possible to set some caching parameters in the web page itself, but I don't suspect they're the issue here.

I tested using different browser and machine. But I got the same content.
Some newly added rows counld not be pulled out and displayed on the website.

It will take at least one business day to display newly added rows. But I could see those rows immediatly from DB. The web page should display all rows but not. I don't know why.
More idea, comments? Thank you!

very helpful. thank you!

Were you able to resolve your problem?  If so, can you tell us what the resolution was?