Many of us do the same thing on Sunday with the sacrament if we give no consideration to the mistakes we made through the week until we are presented with the sacrament.
Repentance should be more about change than asking for forgiveness. If you are forgiven a hundred times over but never change you haven't accomplished anything. If you change, and then are forgiven you have completed the process provided through the atonement by which we become celestial beings.
I believe that God forgives us every time we ask. But are we taking that forgiveness in vain if we do so without making any effort towards change?
Alma 34:32
For behold, this life is the time for men to prepare to meet God; yea, behold the day of this life is the day for men to perform their labors.