Ich requires fish for a portion of its lifecycle. If your tank has no fish in it the ich will die off. One month is usually recommended. After that the tank should be ich-free. Your live rock and live sand will be fine.
You should consider setting up a quarantine tank so this does not happen again.
How were the fish treated? The moderators usually recommend either hyposalinity (preferred) or copper. Most other treatments have low success rates.