Actually Miguel, you can do this any number of times in a file. Each time you change which drawing the autotext will reference you will find the new drawing to determine the scale in the autotext listed.
When you open the Autotext dialogue box, set the category to the drawing you just set as its reference; you will find the drawing name listed under category.
When you move on to another drawing e.g. "drawing 2" and set that to be the autotext reference, then you will find "drawing 2" listed under Category.
If you change the scale of a drawing, or any other parameter for which their is autotext, you can select the text block and renew it and the scale etc will update.
It can be tedious to do this for many drawings, but sometimes that is the right solution when you are using the title block for something else.
HTH
Erika
Architect, Consultant
MacBook Pro Retina, 15-inch Yosemite 2.8 GHz Intel Core i7 16 GB 1600 MHz DDR3
Mac OSX 10.11.1
AC5-18
Onuma System
"Implementing Successful Building Information Modeling"