Load the appendix package with its titletoc option and use the appendices environment to enclose your appendices; this will add "Appendix" to the entries in the ToC. To Add "Appendix" to the headings in the document, a redefinition of \FormatBlockHeading (the style used by mwrep.cls to typeset chapter headings) will be needed. The following example shows these modifications:
\documentclass{mwrep}
\usepackage[titletoc]{appendix}
\begin{document}
\tableofcontents
\chapter{Blabla}
Aaaa
\chapter{Lablab}
Silly equation \ref{eq:silly} in appendix \ref{ap:1}.
\begin{appendices}
\makeatletter
\renewcommand*\FormatBlockHeading[1]{%
\leftskip\@titleindent
#1{\noindent
\ifHeadingNumbered
\@chapapp\ \mw@seccntformat\HeadingNumber
\fi
\ignorespaces\HeadingText\@@par}
}
\makeatother
\chapter{Something more}\label{ap:1}
\begin{equation}\label{eq:silly}
2+2=5
\end{equation}
\end{appendices}
\end{document}
An image of the resulting ToC:

and an image of the first page of the appendix:

To change the word "Appenidix", if you are not loading babel, you can say
\renewcommand\appendixname{New Name}
in the preamble; if you are loading babel, you'll need
\AtBeginDocument{\renewcommand\appendixname{New Name}}
\AtBeginDocument{\renewcommand\appendixname{New Name}}– Nicolás Ozimica Nov 09 '16 at 02:20