You can do a few things:

 

Use it as an XREF instead of a Block.  That way, whenever you update it, it will automatically be updated in every drawing in which it's Xref'd, without any action on your part.

 

Erase it in the target drawing and Purge its definition, then re-Insert it from the updated file.

 

Use -INSERT [with the hyphen prefix], and for the Block name, give it YourTitleBlockName= [with the equals sign at the end].  The = means "go find this as a drawing file with the same name as the Block."  I assume it's in your Support File Search Paths list somewhere.  Answer Yes when it asks whether you want to redefine it, and the Block definition will be updated.  You can then cancel the command without completing the Insertion of another one.

 

If you copy/paste it the block that you "import" will be updated conformably to the one existing in your file.

If you want to "import" an updated block with copy/paste you will have to paste it exploded and "re-block" it a new inside your file with the same name, insertion point, etc.

 

The best for you is to make your tittle block a separated file, then when you INSERT it as a complete file ( to become a block inside your file ) AutoCAD will ask you if you want to update ( or not ) the incomming file ( to become a block inside your file ).