Use these filters to change the text of the "Next" and "Prev" pagination on the singular portfolio views.

ava-portfolio-pagination-text.php

function ava_child_portfolio_prev_text() {
	return 'Previous';
}
add_filter( 'ava_portfolio_pagination_prev', 'ava_child_portfolio_prev_text', 10, 1 );

function ava_child_portfolio_next_text() {
	return 'Continue';
}
add_filter( 'ava_portfolio_pagination_next', 'ava_child_portfolio_next_text', 10, 1 );