Most recipes, but not yet all, support replacing an input or an output.
The best solution, though not officially supported, is to use our API to change the settings of the existing datasets.
IMPORTANT NOTE: Generally speaking, just changing the type of a dataset will not magically work. However, in the specific case of SQL datasets, they are fairly easily substitutable: you just need to change the "type" and "connection" params.
The following code (which can run in a notebook) would do this (you have to go to Settings to add a new API key)