I recently added the TalDorei blood domain cleric subclass to my collection and have been trying to update my D&D Beyond character sheet.  It appears to me that the subclass ability bloodletting focus, which adds 2 + spell level necrotic damage to instantaneous spells, is not being added to the damage of my spells.  Is there a way to get the character sheet to apply the damage buff appropriately (recognizing it increases when spells are upcast)? 

Unfortunately not, no.

Wow, that is unfortunate.  I'm pretty sure I could program it at the spell level in Roll20.

You could probably do it at the spell level here too, but you would have to individually adjust each and every spell and then remember to use the adjusted homebrew version of each spell instead of the standard version.

Homebrew per character is easier on Roll20 because literally everything is a variable you can add and edit as you want. This makes it a superior homebrewing system - but it's a steeper learning curve, the UI is terrible and referencing things is a chore. Character Creation is a horribly long and laborious process, even with their character builder that is woefully inefficient. Also homebrew is designed specifically as a "sheet" thing only.  

D&D Beyond is better at character building, cross-referencing and is oftentimes a more convenient character managing tool. While the homebrew making tools allow static homebrew you can use easily across multiple characters -- homebrewing is considerably inferior. This is because the initial architecture is very rigid - with many things hardcoded rather than being variables that can be easily edited per character. Homebrew was an afterthought. So it gives a more convenient system with features more able to interact, but your per-character homebrewing is much more difficult. Even things you can still do by the code setup is still locked away from you because they didn't update it into the public homebrew tools (for example: race and subclass can let you add spells to the character that can use spell slots, but feats cannot and feats, subclass and race can all add actions to the sheet but items cannot -- there is no reason for these discrepancies other than the devs just not bothering to add them). 

Even non-homebrew official things can be difficult to implement with D&D Beyond's rigid system - which, by dev admission was made lacking forethought. It was built to accommodate the basic "rules as written" for the core rules and everything else has been added in a hodge-podge kinda way because the architecture doesn't make it easy to add anything. 

 -

Also... You're using a homebrew version of the subclass. Blood Cleric is from Tal'dorei Reborn which is not actually available on D&D Beyond. So whenever you use a homebrew you should expect there will be things not working - especially if it is a feature not yet already being used officially. 

You can just remember and do the math in your head. 

But, if you want to use the dice roller for convenience: Your best option is creating a spell "Bloodletting Focus Damage" which just lists damage, that is upcastable as needed and editing the subclass to add it to "work with spell slots" - this will give you something you can then just click to roll the right damage. You will still have to remember to click on it though. 

It's a little odd and clunky but should work.

So I figured out an easier way to add the "clickable" damage as a spell on the sheet without having to edit the subclass (which you probs cannot do since you're using homebrew that is probably shared with you). 

 It was easier to show it, so here is a video showing how to make and add the spell:

Thanks, Cyb3rM1nd!  This is exactly what I was looking for.