@Rene Vizcarra so it is a bit confusing about your situation. If your current hard money lender won't lend more than 50% of the original purchase price, it means they don't see the value in the property either now or in the future. That is a huge red flag. Based on what you are saying it causes me to question whether or not the end product has the value that you see in it. Not saying you are wrong just makes me pause.
In addition, the fact that the original hard money lender has sold the note is another flag of caution. Some lenders to sell their notes but many do not unless it is a distressed situation. Still you might be able to get the new note holder to negotiate with you as others have suggested.
You mentioned having other properties. If one of those properties is paid off, then many hard money lenders will allow you to cross collateralize and increase the loan amount.
I have used a hard money lender that will loan in 2nd position for the additional collateral to increase your loan amount on the subject property. These lenders are much fewer as it takes significant effort and additional funds to foreclose on a 2nd lien and take out the first position on the collateral property to get their money back.