What should I do if I lose situational awareness while in the pattern?
It is the advice of the FAA that you should be looking out the window quite a bit when VFR in the pattern. According to this AC related to traffic patterns:


  Collision Avoidance. The pilot in command’s (PIC) primary
  responsibility is to see and avoid other aircraft and to help them see
  and avoid his or her aircraft. Keep lights and strobes on. The use of
  any traffic pattern procedure does not alter the responsibility of
  each pilot to see and avoid other aircraft. Pilots are encouraged to
  participate in “Operation Lights On,” a voluntary pilot safety program
  described in the AIM, paragraph 4-3-23, that is designed to improve
  the “see-and-avoid” capabilities.


If you are worried you should (over) self announce, if you lose track of an aircraft you should do every thing in your power to make sure that the other aircraft know where you are in the pattern. 


  Self-Announce Position and/or Intentions. “Self-announce” is a
  procedure whereby pilots broadcast their aircraft call sign, position,
  altitude, and intended flight activity or ground operation on the
  designated CTAF. This procedure is used almost exclusively at airports
  that do not have an operative control tower or an FSS on the airport.


The FAA also offers lots of advice on how to fly a pattern here.