The Collaborative International Dictionary of English v.0.48:

Pluries \Plu"ri*es\, n. [So called from L. pluries many times,
   often, which occurs in the first clause.] (Law)
   A writ issued in the third place, after two former writs have
   been disregarded. --Mozley & W.
   [1913 Webster]

Bouvier's Law Dictionary, Revised 6th Ed (1856):

PLURIES, practice. A term by which a writ issued subsequently to an alias of
the same kind, is denominated.
     2. The pluries writ is made by adding after we command you, the words,
"as often times we have commanded you." This is called the first pluries,
the next is called the second pluries, &c.