There are some configuration changes you will have to make in Wordpress. If you are using plugins, there may be even more configuration changes you have to make. For a simple, basic installation with no plugins you will have to change the URL in the "WordPress Address (URL)" and "Site Address (URL)" in the Wordpress admin screen to reflect the new URL after your move. You can find these two options in Settings => General. Then you should be able to copy and paste all of your Wordpress files from the directory they are currently in to the root directory.
If you have a simple setup, moving up a directory will be pretty easy. Shouldn't take you more than a couple of minutes. I wouldn't bother with exporting, reinstalling, and then reimporting. You shouldn't need to. And I certainly would not recommend an htaccess redirect for a move that may be very simple.
If you are using plugins, things may or may not be more complicated. Read the link above for more details.