Assistance with redoing porch

This cedar porch is in the Adirondack Mts of NYS.  The porch is open but there is a roof that protects most of the surface except the edges which have been severely affected by the weather.  The porch is over 50 years old and was originally painted every few years.  When it was stripped we applied Olympic Maximum transparent stain every few years which seemed to keep it in pretty good shape.  The edges of the porch have separated and deteriorate quickly because of freezing water that penetrates despite our attempts to caulk.  For the past couple of years, we have just lightly sanded and applied the Olympic clear coating to preserve what we have. The edges now look very worn but the rest of the porch is in pretty good shape.

We would like to know how to fill the gaps and also how to rejuvenate the rest of the porch so that it matches.