Here's a solution that uses the titletoc package to help with the formatting.

There are a couple of important things in the code below:
\begingroup
\makeatletter
%\listoffigures
\chapter*{List of Figures and Tables}
\@starttoc{lof}
\let\clearpage\relax
%\listoftables
\@starttoc{lot}
\makeatother
\endgroup
This enables us to use our own title for the combined list of figures and tables by using the \@starttoc command; note that it is used twice, one for each of the lof and lot.
The customization of each entry is achieved using
\titlecontents{figure}
[0pt] % left margin
{\addvspace{.5cm}}% % above code (e.g vertical space)
{\contentsmargin{0pt} % numbered entry format
Figure~\thecontentslabel%
\large}
{\contentsmargin{0pt}\large} % unnumbered entry format
{\titlerule*[.5pc]{.}\contentspage} % filler-page format (e.g dots)
%[\addvspace{.5pc}]
You can tweak this as you see fit.
% arara: pdflatex
% arara: pdflatex
% !arara: indent: {overwrite: on}
\documentclass[12pt,twoside,titlepage,headinclude]{scrreprt}
\usepackage{titletoc}
\titlecontents{table}
[0pt] % left margin
{\addvspace{.5cm}}% % above code (e.g vertical space)
{\contentsmargin{0pt} % numbered entry format
Table~\thecontentslabel%
\large}
{\contentsmargin{0pt}\large} % unnumbered entry format
{\titlerule*[.5pc]{.}\contentspage} % filler-page format (e.g dots)
%[\addvspace{.5pc}] % below code (e.g vertical space)
\titlecontents{figure}
[0pt] % left margin
{\addvspace{.5cm}}% % above code (e.g vertical space)
{\contentsmargin{0pt} % numbered entry format
Figure~\thecontentslabel%
\large}
{\contentsmargin{0pt}\large} % unnumbered entry format
{\titlerule*[.5pc]{.}\contentspage} % filler-page format (e.g dots)
%[\addvspace{.5pc}] % below code (e.g vertical space)
\begin{document}
\begingroup
\makeatletter
%\listoffigures
\chapter*{List of Figures and Tables}
\@starttoc{lof}
\let\clearpage\relax
%\listoftables
\@starttoc{lot}
\makeatother
\endgroup
\newcount\tmp
\tmp=0
\loop
\advance\tmp by 1
\begin{table}[!htb]\caption{}\end{table}
\begin{figure}[!htb]\caption{}\end{figure}
\ifnum\tmp<5 \repeat
\end{document}
\listoffiguresand\listoftables. However, those definitions are class-specific. You need to tell us which class you're using by editing your question and adding a minimal working example (MWE). – jub0bs Feb 27 '14 at 09:59