There is no need to specify every upper and lower case. Also, the first part is the most important part because it tells you what floor you on. Floor itself isn't that interesting and doesn't change.
You can use two arrays to search and replace, something like:
var find_arr=["ground","first","second"];
var repl_arr=["Gr. Floor","1th. Floor","1th. Floor"];
Also, you can use the /i modifier at the end of your regex to indicate case insensitive. That way you can do without the confusing [E|e][[T|t]...
http://www.w3schools.com/jsref/jsref_obj_regexp.asp[
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Also... I wouldn't even check specifically for roman numbers and just show an error message when the user wants to commit. Just give the people some good information about what is expected and by giving some examples it will be even more clear. The same goes for "floor". If people can only input floor numbers then there is no need to check for floor because it can be discarded. It doesn't give anymore info on what floor is entered. You could even question why people need to do the extra typing.
Good luck!