I used level up cards to level up my silver Kenshi to the max level of 50 however the XP bar below show 140,095/493,000 as shown in the screenshot. No matter what battle I play with Kensi this figure doesn't increase. 
Does this mean I didn't level up Kenshi to the fullest? or is there any other possibility that I can fill the XP bar?
2 Answers
This happens if you use a level up card to reach level 50, it overshoots. 50 is still the max level, so you not getting any more XP is the correct behavior.
2From this post, 50 is the max level for cards. This spreadsheet shows you the stats for all cards at minimum level (level 1, fusion 0) and at maximum level (level 50, fusion VII).
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