Similar to my previous post SharePoint 2010 – Deploying Webpart Solution, the upgrade process of a Webpart Solution you have a few steps to take to make this all happen.

As I did in my previous post:

I copied the webpart to the local disk of my SharePoint 2010 server. Placing it in a folder c:install this time around I am not going to be running the command Add-SPSolution c:installSharePointWebpart.wsp as it already exist. If you do you will get an error stating that the solution already exists.

What you will need to do is run the following command for example: Update-SPSolution –Identity SharePointWebpart.wsp –LiteralPath c:installSharePointWebpart.wsp –GACDeployment

For more info on features and solutions cmdlets: