most add-ons are really blocks.
I write most of the blog app here on the marketplace, and mostly you have to have a bit of the planning down...the page_types don't need refreshed, although if you do add a singlepage you need to set the installer to add those if not already present, things like that. If you use update command which essentially adds if not present or updates with sql stuff you are good there as well. Concrete5 provides the methods to refresh blocktypes which can be called in a package installer method, but generally for the stuff out there right now and with the 1.1 blog release I am calling the block refresh methods but still recommending that they do it manually as it is a whole 3 clicks :)
I write most of the blog app here on the marketplace, and mostly you have to have a bit of the planning down...the page_types don't need refreshed, although if you do add a singlepage you need to set the installer to add those if not already present, things like that. If you use update command which essentially adds if not present or updates with sql stuff you are good there as well. Concrete5 provides the methods to refresh blocktypes which can be called in a package installer method, but generally for the stuff out there right now and with the 1.1 blog release I am calling the block refresh methods but still recommending that they do it manually as it is a whole 3 clicks :)
re-download and replace the block?
download the latest, stick it back in /packages/ and look at the installed list on the left of your add functionality page in dashboard for an edit >refresh button for that block.
check out the refresh button for addons.
regards