H. J. A. Sire speculates in The Knights of Malta (p71) that the Spanish fleet would quickly move and retake the island, had the siege been successful. The same claim is made - in passing - in Tim Willocks' historical novel, The Religion. If the siege had been successful, the Spaniards would appear as liberators, and if their counterattack succeeded, the strategically positioned island would have been theirs (as the Knights Hospitaller would have been purged in the siege).
The claim is supported by the fact that the bulk of Don Garcia's relief force only arrived in the island a day before the four-month-long siege ended, and only after it became obvious that the Turks wouldn't succeed in conquering the island.
Do we know of a concrete plan for retaking the island? Were there any actual preparations? I'd appreciate answers supported by contemporary or near-contemporary Spanish sources.