You can use \leaders:
\documentclass{article}
\newcommand\asteriskfill{\leavevmode\xleaders\hbox{$\ast$}\hfill\kern0pt}
\begin{document}
\noindent
\asteriskfill
Some reference text reference text reference text reference text reference text reference text reference text reference text
\end{document}

Using something like
\newcommand\asteriskfill{\leavevmode\xleaders\hbox{$\ast\ $}\hfill\kern0pt}
will space out the asterisks.
Inside a tabular:
\documentclass{article}
\newcommand\asteriskfill{\leavevmode\xleaders\hbox{$\ast\ $}\hfill\kern0pt}
\begin{document}
\noindent
\asteriskfill
Some reference text reference text reference text reference text reference text reference text reference text reference text\par\bigskip
\noindent
\begin{tabular}{p{4cm}p{5cm}}
\hline
column1 & column2 \\
\asteriskfill & \asteriskfill \\
column1 & column2 \\
\asteriskfill & \asteriskfill \\
column1 & column2 \\
\asteriskfill & \asteriskfill \\
\hline
\end{tabular}
\end{document}

\leadersfail? – egreg Mar 01 '15 at 23:47\leadersinside a table and I didn't see a problem. Add to your question some example code showing the real context in which you need the asteriks and why\leadersfails. – Gonzalo Medina Mar 01 '15 at 23:56\hfilland not\hfil. If you constructed a proper MWE, it would have taken 30 seconds to give you this answer. – yo' Mar 02 '15 at 00:12