There is a time-honored custom to remain awake throughout the night of Shavuot to recite the "Tikkun" and study Torah. Synagogues commonly provide refreshments and drinks, particularly tea, coffee and soft drinks, throughout the night, and people often drink several times over the course of the night. The question arises, must such a person recite the Beracha of "She'hakol" each time he drinks, or does the Beracha recited over the first drink cover all subsequent drinking throughout the night?
According to Halacha, the Beracha of "She'hakol" recited over the first drink indeed covers all drinks drunk thereafter. This applies even if one drinks in long intervals. Thus, for example, if a person drinks when he arrives in the synagogue at 11:00 PM, the "She'hakol" recited then covers even the cup of coffee he drinks before Shacharit at 4:00 AM. Preferably, one should have in mind while reciting "She'hakol" over his first drink that the Beracha should extend to all drinks drunk throughout the night.
The exception to this rule is a case where a person leaves the synagogue at some point during the night, such as for fresh air or to walk around the block. If he decides to drink after returning to the synagogue, then he must recite a new Beracha of "She'hakol," as the first Beracha was disrupted by his exiting the synagogue. Even though the people with whom he had been when he drank initially remained in the same place inside the synagogue, he must nevertheless repeat the Beracha when he drinks upon his return to the synagogue.
It should be noted that this applies in all situations, not only on Shavuot night. If a person recited "She'hakol" over a drink, and after drinking he briefly stepped out of his home, if he wishes to continue drinking upon returning inside he must repeat the Beracha of "She'hakol."
(Based on Chazon Ovadia Laws of Yom Tov, p. 311)
Summary: The Beracha of "She'hakol" recited over a drink in the synagogue on Shavuot night covers all drinks drunk throughout the night, provided that one remains in the synagogue. If at any point he leaves the building, then upon returning he must recite a new Beracha of "She'hakol" when he drinks again.
