app/soc/templates/modules/gsoc/proposal/_buttons_update.html

{% if is_pending %}
  <input type="submit" name="action" value="Update" class="submit" />
  <input type="submit" name="action" value="Withdraw" class="submit" />
{% else %}
  <input type="submit" name="action" value="Resubmit" class="submit" />
{% endif %}