Recalculation of a table is normally not automatic, but needs to be triggered by a command. See Advanced features, for a way to make recalculation at least semi-automatic.
In order to recalculate a line of a table or the entire table, use the following commands:
Recalculate the current row by first applying the stored column formulas from left to right, and all field/range formulas in the current row.
Recompute the entire table, line by line. Any lines before the first hline are left alone, assuming that these are part of the table header.
Iterate the table by recomputing it until no further changes occur. This may be necessary if some computed fields use the value of other fields that are computed later in the calculation sequence.
Recompute all tables in the current buffer.
Iterate all tables in the current buffer, in order to converge table-to-table dependencies.