Basic force regen stays always same, 8 force per second. While you keep Concentration buff up, it's up to 10.4 per second. But do a little math - disturbance 30, Project cost 45 force, weaken mind 35, TK wave 50, forcequake 100 force... Add there occasional Force Shield (65 force!), stun and even heal (50 or 55 force).
Just try to use more disturbance / tk throw and less .. of everything else - atleast to level 25-26 when you should pick Telekinetic Effusion asap - it will help a lot! I dare to say it's the most important talent in whole TK tree - and main reason for hybrid tk / balance builds. But even so, you will need to prioritize. I personally don't use Weaken mind on anything less than Elites (Golden enemys) - but that's for mine 900+ bonus damage sage. As strong targets for me die much faster than weaken mind's duration. Forget Project in standart rotation, use it only for stunning standart mobs - (and then use Trumult on them Or when you are forced to run around only.
At 50 both full TK and Balance builds (assuming they want to provide highest possible DPS) Will run out of force - frequently need to leave some abilities from they 'best' rotation. If they are forced to off-heal / Shield up etc, they drop down with theyr pools quite a bit. Regaining of force is for both then very slow. Full Balance is actually better at force regain then full TK.
At 50 there is only one spec which can truy say that does not have force regen issues - hybrid tk / balance as having both Telekinetic Effusion and Psychic Barrier. At lvl50 with 2 pieces of PvE set and with 'Inner strenght' your TK throw will cost (with TK effusion buff up) only 13 force - but will still restore 4% of your force = 20 (if you have Mental longevity then you regain 24 force!)
Example of TK / Balance build :
Assuming you cast TK throw 3x in 9 seconds (for easier math)
Due to each tick of TK throw may proc TK effusion, even less than 30%+ crit chance you will have this proc virtually ALL the time up.
In 9 sec you spend 3*13 = 39 force . But it will restore 3*4 = 12% of your Total force refunded = 72. Net gain 33 force - and offcourse your still regain your normal 72 force (9*8 per second regen). = 33+72= 105
force Regained after 9 seconds...
While you are actually casting your highest dps ability - and cntributing ¬80-90% of your maximum dps anyway...
Full TK build with Pv\E set bonus, Inner Strenght example =
in 9 seconds you cast 6 Disturbances = 6*13 = 78 Force spend - If your get lucky and crit every second cast., no refunds - concentration up 3x all the time. But that just won't happen, you will have few Disturbances at full force cost (26), which in a very unlucky row can be all 6 non-crits = 156 force spend.
You total regain 9*10.4 force = 93.6 force. In 9 seconds you just did only regain 15.6 force in best case scenario, or in worst case lost 156-93.6 = 62.4 force...
Full balance (With mental longevity and inner strenght) Is actually pretty close to be fully neutral - keeping high dps while keeping your force pool neutral. But it may not be as fun as throwing giant 'forceballs'