Log in to your Autodesk Account and navigate to the Product Updates section. You can use filters to find "AutoCAD LT" and the specific "2019.1" version.
Sometimes updates can change how user preferences work. If you find you can no longer double-click to edit text: Autodesk AutoCAD LT 2019.1 Update Only
If you have the Autodesk desktop application (now called Autodesk Access) installed, it should automatically notify you of available updates for your installed software. If you want to select "Text Only" in your drawing Log in to your Autodesk Account and navigate