Use Saved Replies
Click the "Bookmark" icon, Search for and choose your Reply
Step 1: In the "answer field" press the "Bookmark" icon to open your Saved Replies
Step 2: Search for a word and you will be presented with all Saved Replies containing that word, as well as a preview of the message.
Step 3: Click the message to insert it into your answer field
You can always choose to edit your answer before sending.