There are several processes of change that affect spoken languages, including phonological and phonetic change, semantic change and lexical replacement. Each of these categories, in turn, comprise a large set of complex phenomena, such as all the types of phonological change (epenthesis, elision, metathesis and so on). In any case, all spoken languages undergo the same processes, although at different rates, with different results etc.
Is this also true for signed languages? That is, are signed languages affected by the same processes – albeit "translated", so to speak, to the domain of signs and facial expressions – that affect spoken languages?