Here's how to purge and replace a layer in your site:

The "Update existing features or create new features" function allows you to completely replace all of the features in a dataset. Similar to appending data, you have to ensure that the number, type, and name of all fields in the new data match what is already defined for this layer's data source.

The dataset is updated using the Unique IDs of the existing records in your dataset; therefore, you will need to ensure that your data has a Unique Field specified. To learn how to set a Unique Field, you can read our support article here.

1. Open the LAYER ADMIN panel. 
   
   
2. Click on the Data Sources tab.
   
   
3. Choose your data source.
   
   
4. Click "UPDATE" in the data section and choose your new data.
   
5. Upload your data.
   
   
6. Click "Update" and your new data now replaces the old data.