Any process that activates or increases the frequency, rate or extent of mitotic spindle elongation.
Synonyms:
exact_synonym:
positive regulation of spindle elongation during mitosis; up regulation of mitotic spindle elongation; up regulation of spindle elongation during mitosis; upregulation of mitotic spindle elongation; upregulation of spindle elongation during mitosis
narrow_synonym:
activation of mitotic spindle elongation; activation of spindle elongation during mitosis