If your visa is refused or your application for indefinite leave to remain you need to know what the reason for refusal is first before you can make any decisions. Many decisions could be overturned by the assistance of a high level consultant (this will cost you a lot). It will all depend on why first. If you where refused for sending in fake documents, undisclosed criminal activity and similar subjects then appealing will seem unlikely to succeed.
If your application was refused on a different issue such as too many days outside the country or other somewhat minor reasons you may have a case to appeal. If you are preparing your application now and want to avoid being in this situation where you may have to leave your job and the country then buy our guide and learn how to prepare your documents now and what to expect when you apply. also consider applying using same day application service to give yourself the best chance of success and avoid having a refusal after your visa expires.