One more undergraduate year for grad school?
Generally speaking, no one cares all that much how long it took you to finish your undergraduate degree.  An extra semester or even an extra year will make almost no difference to anyone.  They will care what your GPA was.

One of my service assignments as faculty at UMich in our CS department is undergraduate advising.  I am constantly having to remind students that it does them no good to take a heavy load, hoping to graduate early, if the result is that they crater their GPA.  Much better to take a manageable load they can do well.  Twelve units of straight A's always beats 17 units with a couple of C's, especially for anyone hoping to go on to graduate school where ballpark minimum GPAs for entry to our master's and PhD programs are about 3.6 and 3.8, respectively.