You can formulate this as a dynamic programming problem
Calculate the number of adjacent paths that are ascending
path[i][j] = 1 for all i,j
for i=0;i
The answer will be max(path[i][j])
for all i,j.
Or recursively, if you prefer
for i,j0 return path[i][j]
ret = 1;
for dirx, diry in [(1,0),(0,1) ... etc ... ]
if arr[i+dirx][j+diry] = arr[i][j] + 1
ret = max(ret, go(i+dirx,j+diry))
return ret