The Bet Yosef (commentary to the Tur by Maran, author of Bet Yosef) brings a ruling of the Rashba (Rav Shlomo Ben Aderet of Barcelona, 1235-1310) concerning a person who recited a Beracha over an ordinary fruit (in the Rashba’s case, it was an Etrog), and also had in front of him an olive. The Rashba maintained that since olives are among the Shibat Ha’minim – the seven special species of the Land of Israel, it is considered a superior fruit, and, as such, it is not covered by a Beracha recited over an ordinary fruit. Although normally a Beracha recited over one product covers all foods requiring the same Beracha that are served afterward (unless one specifically intended to limit his Beracha to that food), this rule does not apply, according to the Rashba, when the subsequent food product is considered superior.
Although the Rashba’s ruling is not mentioned in the Shulhan Aruch, it is nevertheless accepted by Halacha. This is the position of both Hacham Bension Abba Shaul (Israel, 1924-1998) and Hacham Ovadia Yosef, who noted that the Bet Yosef mentioned this ruling without bringing any differing opinions, indicating that it is to be accepted.
However, these Poskim do not go so far as to accept the Rashba’s ruling in a case where both foods were present on the table when the Beracha was recited. In such a case, the Beracha covers both foods, even if it was made on the inferior food. However, if one made a Beracha on an inferior fruit, and then a superior fruit was brought to the table, one must recite a new Beracha – even though generally a Beracha is not repeated when another food is brought that requires the same Beracha as one which was already recited.
Another example of this Halacha is the case of one who recited "Mezonot" over pasta, and then cookies were brought to the table. Cookies and similar baked goods are considered "superior" to pasta because theoretically, one who eats a very large quantity of cookies will need to recite Birkat Ha’mazon, which is not the case with pasta. Therefore, one would have to repeat the Beracha of "Mezonot" over the cookies when they are brought to the table.
There is considerable debate, however, as to how precisely we determine "inferiority" and "superiority" with respect to this Halacha. For example, if a person personally prefers a certain fruit over fruits from the Shibat Ha’minim, it is uncertain which fruit is considered "superior." Therefore, in order to avoid this question, it is preferable whenever reciting a Beracha to have specific intention for the Beracha to cover all foods requiring that Beracha which will be brought afterward. This way, according to all opinions, he will not have to repeat the Beracha.
Summary: Generally speaking, if a person recited a Beracha and ate, and then another food requiring the same Beracha is served, he does not repeat the Beracha. An exception to this rule is a case where a superior food is brought – such as if one recited "Ha’etz" over an ordinary food, and then one of the seven special species was brought; or if one recited "Mezonot" over pasta, and then baked products were served. In these cases, the Beracha must be repeated over the superior food. However, as it is not always clear which food is "superior," one should preferably have in mind whenever reciting a Beracha that all foods he will eat afterwards requiring that Beracha should be covered. This way, he can be certain that he does not need to repeat the Beracha.