Does a breast implant that has fallen below IMF fold need revision using strattice in order to prevent dropping again?

I am sorry to hear about the problem you are having after breast augmentation surgery. 
 Generally, signs of breast implant bottoming out include: 
1. Breast implant "sits" too low on the chest wall.
2.  Excessive palpability or visibility of the breast implant along the lower breast pole.
3.  Nipple/areola complex seems to be sitting relatively high, because the breast implants have settled too low. 
4. Discomfort along the lower breast pole (secondary to pressure from the underlying implant).
5. Relative paucity of upper pole breast implant volume compared to lower pole volume.
6. Increased visibility of a infra mammary fold scar (higher on the breast mound).
 Patients who experience bottoming out of breast implants typically benefit from revisionary breast surgery which will likely involve capsulorraphy ( internal suture repair). Sometimes, depending mainly on the patient's history and physical examination, I will also use additional supportive materials such as acellular dermal matrix or biosynthetic mesh. This procedure serves to reconstruct the lower poles of the breasts and prevent migration of the breast implants too far inferiorly. Associated issues with positioning of nipple/areola complexes and visibility of the inframmammary fold scars (if present) should improve with this operation.
There are several important "factors" involved in this type of revisionary breast surgery. Most important (in my opinion): plastic surgeon experience level.     In other words, experience level and technical expertise play the biggest role when it comes to successful  outcomes with this type of revisionary breast surgery.   Careful attention to postoperative activity limitations as well as use of appropriate postoperative support of dressing/garments are also important.
 I hope this helps.

The answer depends on why the bottoming out occurred. It is typically because the tissues thinned leaving inadequate support, and this happens more often with large implants. However yours are not especially large and since it only happened on one side, you might be able to get by with capsule repair (capsulorrhaphy) alone. Galaflex mesh is a less expensive option than Strattice, though Strattice has a longer record of clinical use for this application.

It's possible to correct bottoming out with a repair of the capsule alone or in combination with mesh support such as Strattice (permanent) or Galaflex (resorbable). Exam of your tissues and photos would be important to give you more recommendations. Consult with a few surgeons in person for a detailed exam.Best wishes,Dr.Bruno