I got it working now. I added a checker of the alarm time and current time.
public setAlarm(String time, Context context){
String[] strTime;
strTime = time.split(":");
int hour, min, sec;
//set when to alarm
hour = Integer.valueOf(strTime[0]);
min = Integer.valueOf(strTime[1]);
sec = 0;
long _alarm = 0;
Calendar now = Calendar.getInstance();
Calendar alarm = Calendar.getInstance();
alarm.set(Calendar.HOUR_OF_DAY, hour);
alarm.set(Calendar.MINUTE, min);
alarm.set(Calendar.SECOND, sec);
if(alarm.getTimeInMillis() <= now.getTimeInMillis())
_alarm = alarm.getTimeInMillis() + (AlarmManager.INTERVAL_DAY+1);
else
_alarm = alarm.getTimeInMillis();
//Create a new PendingIntent and add it to the AlarmManager
Intent intent = new Intent(context, AlarmReceiverActivity.class);
PendingIntent pendingIntent = PendingIntent.getActivity(context, 19248, intent, PendingIntent.FLAG_CANCEL_CURRENT);
AlarmManager am = (AlarmManager) context.getSystemService(Activity.ALARM_SERVICE);
am.setRepeating(AlarmManager.RTC_WAKEUP, _alarm, AlarmManager.INTERVAL_DAY, pendingIntent);
}