How can I refresh an email in the native gmail app? I get many emails with pictures in them.  When I try viewing them in the native gmail app, it displays some of them, but not all.  The only way to view the undisplayed ones is to preview them one at a time.

Is there any way to tell the app to refresh the current email?
Go to Inbox, press MENU button and click on Refresh. Now, open the email again. 

In the Gmail app, there is no way to refresh the current email, you can only refresh your Inbox.  When you refresh Inbox, emails are downloaded(in text format) to your inbox. Images from the email were downloaded on opening the email.