Statute of Limitations for Tortious Interference with Existing Contract

If someone tortiously interferes with a contract that I am a party to, is there a limited time within which I must file a lawsuit?

Yes.  As a general principle of Texas law, tortious interference with an existing contract has a two-year limitations period.  See First Nat'l Bank of Eagle Pass v. Levine, 721 S.W.2d 287, 289 (Tex. 1986); see also Khan v. GBAK Props., Inc., 371 S.W.3d 347, 356 (Tex. App. – Houston [1st Dist.] 2012, no pet.).