Kitzur Shulchan Aruch, Rabbi Shlomo Ganzfried
Chapter 57 : Laws Relating to Berachos over Food and Drink Served in Addition to the Original Fare
When you recited the berachah over bread you had no intention to eat more then what you had prepared; for instance, you bought bread or a roll thinking that this will be sufficient, but later you desired to eat more; and you sent someone to buy more of the same. Even if there is still some left of what you had orriginally prepared, nevertheless, you must repeat the berachah Hamotzi over the additional bread, because this is a change of mind. But if you had bread in the house, and you cut off one slice thinking that it would be sufficient, but then you desired to eat more, and you cut off another slice, even if there is nothing left of the original slice, and you need not repeat Hamotzi, for this is not considered a change of mind, for this is the usual way [of people].
If you say a berachah over the fruit which you are eating, and then some more food is served, if at the time you said the berachah, you had in mind to include all that would be served, then, even you have nothing left of the original food, and even if [the additional fruit] is not of the same kind as the first but requires the same berachah, you need not repeat berachah over the additional fruit. However, if you clearly changed your mind, that is to say, your original intention was to eat the fruit that was before you, and then you decided to eat more, in that case, [even if the additional fruit] is of the same kind as the first, and there is still in front of you some of the original fruit, nevertheless, you must repeat the berachah over the additional fruit.
However, if initially you gave no thought one way or the other [about any additional fruit that might be served] then the following distinctions [must be made]: if, at the time the additional fruit is served, none of the first fruit is left, you must repeat the berachah [when you eat the additional fruit], however, if there is still some of it left, it is questionable if a second berachah is necessary over the additional [fruit]. Therefore, it is advisable that you exercise caution, when reciting the berachah, to have in mind [to exempt] whatever may be served later. Now, if you gave no thought [to additional fruit], and had nothing in mind, since it is questionable if the berachah must be repeated, you should avoid eating [the additional fruit].
If [additional] fruit is served, that is, of a superior kind, and it is more appealing to you than the first, or if the additional fruit belongs to the seven species, even if some of the first fruit is still left, you must repeat the berachah over the additional fruit, [because the berachah recited over] a lesser article of food does not exempt a superior one2 automatically, unless you clearly intended to do so.
If you say the berachah [Shehakol] over beer, with the intention that the berachah should exempt all other articles of food that require the berachah, Shehakol, and then fish is brought [to the table], you need not repeat the berachah over the fish. [If, however, when saying the berachah,] you did not think [about any food that might be served later], then, even if at the time the fish is served there is still some beer left, you must say the berachah over the fish. This case cannot be compared to the case of the [different] fruits, where, even though one of the fruits is an apple and the other nuts, both belong to the same category of food, whereas, beer and fish are two entirely different kinds of food, one is food, the other a beverage. [Even though both require the berachah Shehakol] the one cannot exempt the other, unless they are both on the table when you recite the berachah, or you had the intention to exempt it.
The above rules apply only to a person who eats his own food, but if you eat a meal at someone else's house, the berachah you say over one kind of food, exempts all that is being served even if there is no more left of the first course, since [a guest] submits to the host's wishes. But if you actually change your mind [regarding the additional food] then you must repeat the berachah. If the host had no intention to serve more [of the same food], and he only offered it at the request of his guests, even then they need not repeat the herachah, because guests assume that in all likelihood the host will serve them with all the food they desire.
If you come to a meal where you are served a beverage, and you recited the berachah over it, and later you are offered more of the same; if it is the general custom [to serve drinks continually], it may be assumed that you intended to include all the drinks [with the first berachah] and you need not repeat it.