There is no process for being re-indexed.
What happens is, when the sites content changes enough that the bot doesnt see it as 'black hat seo' (the numero uno reason) or 'duplicate content used on multiple domains' (numero dos reason). It then gets moved up a list, the bot has to see its now clean, and gets added to a 'check again' list, and some weeks or months later the bot will return, it all clear, it moved up the list until its added back into the index. This is of course speculation because only a handful of people (who all work for google or have worked for google and signed a non-disclosure know for sure).
I am lead to believe google also bans IP addresses or known offenders webservers, so you should check your IP. Google also uses sorbs and other spam databases in their equasion, so you should check if the domain is blacklisted with the spam agencies, and inform them of a new owner and ask them to remove it. Adding an SPF, closing open relays etc will also help with this.
Also google take into account other websites that link to a website (a'la page rank), so you have to bear that in mind too, kinda annoying that if a cracks website decides to link to you site either as a type or by scraping, it impacts your site.
Unfortunately its going to be a long process over anything from weeks to months.
