Hi Sabrina,
"Reposicionar" is a well-known term in the marketing and advertising industry. Here's a simple definition:
Es como su nombre lo indica, el volver a posicionar en la memoria del cliente cierto producto o servicio que ya había olvidado.
Its equivalent in English seems to be "reposition". Look at the fourth definition below:
re·po·si·tion
n.
1. The act of repositing or the condition of being reposited.
2. The return of something, such as a bone, to its proper position.
tr.v. (r
p
-)
re·po·si·tioned,
re·po·si·tion·ing,
re·po·si·tions
1. To place or put in a new position; position again.
2. To update or change the marketing of (a product or service).
And more specifically:
Brand Repositioning: changing the appeal of a brand in order for it to attract new market segments; brand repositioning may or may not involve modifying the product.
Hope it helps!