You need a special glue capable of withstanding high temperatures. Most epoxies won't last.
Ideally you need to split the door into the two halves - the front facia is normally held on with some brackets that are screwed onto the door - check around the perimeter edge of the door for screws. you may find them on one side only, with the other side clipped in. Once the screws are removed it should be relatively easy to unclip the opposite side.
If you cannot split the door, because the fascia is also glued on, one route is to use a dent puller / sucker, to stick to the glass and manoeuvre it into position. But you will need to find a way to hold the glass in position for quite a few hours whilst the glue dries - so it is not ideal.
You can get a glue kit from http://ovendoorglue.co.uk which has the right type of adhesive for you.
Eddie
December 2009