How can I use notepad++ to do a regular expression ? Extract a tag and replace it

Question

There are too many xml like this format. And also some book tag is included non ASCII

Current:

<Book>apple</Book><title></title>
<Book>蘋果</Book><title></title>

Expect:

<Book>apple</Book><title>apple</title>
<Book>蘋果</Book><title>蘋果</title

I would like to extract the value in the tag and paste it. How can i use the notepad++ to search and replace it. Please help. Thanks!