In a planned community, if the right is originally reserved in the declaration, the declarant, in addition to any other development right, may amend the declaration at any time during as many years as are specified in the declaration to add additional real property to the planned community without describing the location of that real property in the original declaration; but the amount of real property added to the planned community pursuant to this section may not exceed ten per cent of the real property described in subdivision (3) of subsection (a) of section 47-224 and the declarant may not in any event increase the number of units in the planned community beyond the number stated in the original declaration pursuant to subdivision (5) of said subsection.