How i could save a block that i had called it before with block_load?
After reading the code in the block.module file I can suggest the following:


Leave your code in hook_block_info_alter unchanged.
From your hook_enable hook call the following function to force calling and saving your hook_block_info_alter code:

_block_rehash();



Quoting from the function's documentation: 


  Updates the 'block' DB table with the blocks currently exported by
  modules.


Hope this does it for you!