Most servers have services installed like NickServ where if you register with them and set a password, then you "own" the nickname. Try typing /nickserv register help or /msg nickserv register help in the status window and see if you network has services. If that does not work, you may try the #help or #Oper channels and ask for assistance there.
Some networks do not have services however, in which case the only chance you have is keeping your connection 24/7 to "Reserve" your name.