UPDATE 1-Skechers says still wants to buy Heelys

(Writes through; adds details throughout, NEW YORK dateline)

NEW YORK, Aug 21 (Reuters) - Skechers USA Inc (SKX.N) said it was still interested in buying rival shoe maker Heelys Inc (HLYS.O) despite Heelys' rejection of its sweetened $142.8 million bid.

Skechers also said on Thursday that it might be prepared to "refine" its $5.25-per-share offer "if additional value can be identified during the due diligence."

"The company's interest remains genuine and, along with our advisers, we will continue to explore all of our options," Skechers Chief Executive Robert Greenberg said in a statement.

Skechers has already raised its bid once, from an original offer of between $4.75 and $5.10 per share.

Greenberg said he believes the latest bid provides a "full and fair value" to Heelys shareholders and that he is "particularly disappointed that, after repeated contacts over several months, Heelys will not agree even to discussions or provide us with an opportunity to conduct due diligence." (Reporting by Martinne Geller; editing by John Wallace)