Here's a neat trick in Sublime Text 2 or 3 to convert your indentation spacing in a document.
TL;DR:
Converting from 2 spaces to 4 spaces:
Ensure tab width is set to 2. Convert your 2-space indentation to tabs, switch to tab width 4, and then convert the indentation back to spaces.
The detailed description:
Go to:
View -> Indentation
It should read:
Indent using spaces [x] Tab width: 2 Select:
Convert Indentation to Tabs Then Select:
Tab width: 4 Convert Indentation to Spaces Done.