If you have the handle of the uitable (here: myHandle), you can use:
set(myHandle,...
'Data', MyNewData);
with MyNewData as the updated data.
You can also use additional arguments, like:
...
'ColumnName', columnname,...
'ColumnFormat', columnformat,...
'ColumnEditable', columneditable,...
'ColumnWidth', 'auto',...
'RowName',names);
There are a lot more options, not all of them are documented. Have a look here to find out more about undocumented Matlab-features!