From my immense experience and that of my friends, I can tell you CLEARLY that you must not spend more than 2 years cracking UPSC Civil Services Examination. Civil Services (IAS, IPS, etc) is a unique career but let us get realistic. It is not an assured career. Only around 100 aspirants from General Merit (GM) Category will become IAS, another 100 may become IPS and so on.
You try your best in these 2 attempts spanning over 2 years to crack this exam FULL TIME. If you cannot figure out how to prepare full time, then please do not attempt this examination. Having said that, there are some people who are determined and focused. These people somehow maintain a disciplined study schedule along with their work and thus can crack this exam. So, discipline and regular study are very important to crack this exam.
UPSC gives you 4 to 6 attempts and until you reach the age of 30 for a GM candidate but you should not go behind this exam without a back up career plan. More about it in some other post.
Some of my friends who had gone to Delhi to become an IAS officer today are ready to accept any government job including that of a clerk. You should not put yourself in such a position.