The Collaborative International Dictionary of English v.0.48:

Invocate \In"vo*cate\, v. t. [imp. & p. p. Invocated; p. pr. &
   vb. n. Invocating.] [L. invocatus, p. p. of invocare. See
   Invoke.]
   To invoke; to call on, or for, in supplication; to implore.
   [1913 Webster]

         If Dagon be thy god,
         Go to his temple, invocate his aid.      --Milton.
   [1913 Webster]