You loose the format 'cause you're using _cliptext to bring the text back to the richtextbox.

You can use this api function to paste the content without lousing the format:
#DEFINE WM_USER 0x400
#DEFINE WM_COPY 0x301
#DEFINE WM_CUT 0x300
#DEFINE WM_PASTE 0x302
#DEFINE WM_UNDO 0xc6
#DEFINE WM_REDO (WM_USER+85)

DECLARE SendMessage IN user32 ;
INTEGER hWnd,;
INTEGER wMsg,;
INTEGER wParam,;
INTEGER lParam
*And you can use it like this.

SendMessage(THISFORM.Edicion1.OBJECT.Hwnd,WM_PASTE,0,0)

It will work, it worked for me.