How to upgrade or update SharePoint Solutions

Use following PowerShell script to update your WSP:

# Name of your solution
$SolName = "TestSolution.wsp"

#Location of your solution
$SolPath  = "E:\TestSolution\TestSolution.wsp"

# Command to upgrade your soltion
Update-SPSolution -Identity $SolName -LiteralPath $SolPath -GACDeployment -Local