MY VISA EXPIRES ON 4- 1-15. I HAVE MULT. ENTRIES & WENT ONCE. CAN I ARRIVE ON 3-29 AND LEAVE 4-5?

WE GOT IT IN APRIL 2014 AND ONLY WENT ONCE WITH MULTIPLE ENTRIES. OUR ENTRY PERMIT EXPIRES ON 4- 1-15. WE ARE THINKING ABOUT GOING AGAIN AT THE END OF MARCH. WE WILL ARRIVE ON 3-29-15 AND LEAVE 4-5-15. WE HAVE THE DURATION OF EACH STAY FOR 90 DAYS. DO WE NEED TO APPLY FOR NEW ENTRY PERMIT?