Hard question, but for me I would say more fiscal responsibility, less focus on bathrooms, transgenders, and bakeries selling cakes to LGBT people. These are losing issues long-term, the world is changing and they need to react to that reality. Heavy, heavy. focus on stopping government waste, corruption, and greed in bloated government programs that waste far too much money because of the system as it exists right now. (this is a problem for both parties) Focus on extreme transparency in how government projects are created, written, and especially funded with all information easily available on all major spending for scrutiny with multiple audits by non-partisan entities that are also transparent and available for the media/public. Less deficit spending and actually mean it.
Abandon say 500k and more salaries, and focus on a massive tax cut for the middle class without having to break the budget because you haven't cut the top rates. Sacrifice the current healthcare platform and convert to a model more based on utilities and focus on creating a better system for overall healthcare used in many countries that are poorer than us yet have better healthcare outcomes and more efficiency. That's a hugely difficult shift, but healthcare works in a lot of places better than here and with many poorer countries.
Fight on the idea that bloated college debt is always the best route for everyone -- it's not actually. Create real job training for the future in tech/innovative industries to give many Americans the opportunity to bootstrap beyond their starting place in life without having to get 100k in debt for a 30k job that puts you in debt for a decade or longer. The truth is that many jobs here now will be useless in 20 years and they should be the party to have a vision for the future.
Bottom line even more: A VISION for the future, not division and rhetoric. Why did 1994 go so well with them? They actually presented a vision that resonated with people, when is the last time either party actually articulated a true vision versus attack back and forth?
You don't have to budge much on some issues (guns, certain reasonable social issues, tough on crime) as you can't please everyone.
Just these off the top of my head, I bet there is so much more out there I suppose...