(1) Seniority of ships; ships that survived the battle gain on armor, power and initiative. "Run and hide" or not fighting status descreases armor, power and initiative. Maximum bonus of 50% and maximum malus of 25% sounds fair.
(2) Defensive constructions; planets should be able to build defensive constructions such as defense turret. Regular maintenance shall be required else they lose armor and power.
(3) Maintenance of constructions; construction should depreciate and with depreciation they lose efficiency. Constructions eventually become useless if not maintainted.
(4) Roids initiation; instead of simple initiation by buying roids you initiate search for roids (similar to how it was in the first few PA rounds, if I remember right). Sometimes you get lucky, other times you don't. Roids that are not mined (eg. research limits you to 1,000, you have 1,100) can be initiated by other planets, whoever initiates search for roids in that sector first.
(5) Eliminate scan ressearch; this limits individual players and newcomers because they don't have access to scans. They either have to research scan tree and fall back on value or try their luck playing blindly. If a player wants a scan, he or she should get it / buy it. Eg. You get simple scans immediately after purchase (planet scan, development scan), you have to wait one tick for incoming scan, 2 ticks for news and unit scan, 4 ticks for advanced unit scan etc. Initially all scans cost the same, but the price increases with every scan purchase. The tenth scan should already cost at least 50k of each resources.
Reset after 24 hours.